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Searching for Lost Submarines: An Overview of Forensic Underwater Methodologies

By Andrew Song

How does one find an object not meant to be found? Forensic maritime investigators in 2017 stumbled across this question when searching for the disappeared ARA San Juan (S-42) – an Argentinian submarine whose mission centered around stealth. Despite the environmental challenges and the restrictions imposed by the profile of submarines, several complementary forensic tools have emerged as authoritative standards and best practices for underwater search operations. These include: (1) optimization of preliminary search boxes through Bayesian probabilities, with updates for posterior probabilities throughout the search; (2) side-scanning sonar systems; and (3) unmanned underwater vehicles (UUVs) for imagery, access, and identity verification. In explaining the efficacies and drawbacks of such methods, this analysis highlights the importance and evolving future of search optimization strategies.

How to Find a Lost Submarine

Forensic maritime investigators confront distinct challenges not relevant for traditional land-based investigations. Unlike terrestrial-based forensics, pre-established knowledge of a local maritime environment is sparse. Scientists have mapped 1/5th of the sea floor to modern standards with 100m resolution, but that means almost 290 million square kilometers of seafloor—twice the surface area of Mars—have not yet been surveyed.1 Furthermore, the remoteness of submarine operational areas casts a wide speculative net for a submarine’s last location, acting as a red herring for planners. For instance, the French Navy finally found the Minerve in July 2019 after searching since 1968, but the submarine’s position was only 28 miles off the coast of Toulouse.2

Debris from the French submarine Minerve. The letters MINE from the Minerve’s name are visible in the wreck. The Minerve was lost in January 1968. (French Navy photo)

The absence of existing charts, therefore, necessitates simultaneous 4-D mapping of the area—which is in short supply. Submarine debris is unidentifiable in satellite and aerial images due to surface opacity and the extreme depth of wreckages. Stratification conceals wreckage and clearing sedimentary buildup becomes extremely complicated due to sheer volume. An onsite “walk-over” survey, as described by Fenning and Donnelly3 in their description of geophysical methodologies, is simply impossible in a marine environment. Acidity and pH levels of the water also influence rates of decomposition, and must be considered for a simulation in the casualty scenario.

August 1986 – A view of the detached sail of the nuclear-powered attack submarine USS Scorpion (SSN-589) laying on the ocean floor. Depth 10,000 feet, 400 miles southwest of the Azores. The Scorpion was lost on May 22, 1968. (Photo via U.S. National Archives)

1: Bayesian Search Strategies

Constructing a preliminary search box requires meticulous strategizing and calculations. An error associated with misanalysis of primary sources can inevitably mislead search and rescue planners, delaying a submarine’s discovery. This occurred in the case of the USS Grayback, as Navy officials mistranslated the final coordinates of the submarine documented by a Japanese carrier-based bomber.4 An incorrectly interpreted digit in the longitudinal coordinates created an erroneous search area straying 160 kilometers from the Grayback’s actual location.5

Pitfalls in relying on a single source cause planners to use search strategies based on Bayesian statistics. At a rudimentary level, Bayes’ theorem leverages probabilities of an event and prior knowledge regarding the condition of such event to produce a reasonable prediction of an event’s occurrence. Stakeholders will first formulate a range of possible stories surrounding a missing submarine’s location, pulling from all potential sources (eyewitness testimony of submarine’s last submergence, operational logs, mission record, etc.). The credibility and value of each piece of evidence will be judged by investigators and experts who will then collectively assign statistical weight to possible scenarios. For instance, the USS Scorpion’s forensic team invited experienced submarine commanders to present reasonable hypotheses that the scientists would later input into a probability density function.6 Such probability density functions assist planners in prioritizing certain search zones for surveying. Investigators resort to Bayesian statistics and Bayesian inference models because of its predictive power and the comprehensive results derived from relatively few inputs. Figure A demonstrates a four-step hierarchical convention in a Bayesian search strategy. The diagram summarizes the effects of updates on the model and introduces the posterior probability function (PPF).

Figure A.

When a search area fails to yield any evidence pointing to a submarine, a posterior probability function will be calculated. A PPF’s utility and role is best explained by Equation (1-2)’s hypothetical representation of a grid square’s probability of containing a submarine. Variable q represents the probability of successful detection of a wreck and p quantifies the probability that the grid square does contain the wreck. Failing to find a wreck in a grid square will revise the probability of that grid square into p prime—a posterior probability.7 In this theoretical situation, the probabilities (for purely illustrative purposes) are: that a wreck in the grid square is 67% and the chances of a side-scan sonar identifying an anomaly is 85%.

Under those numeric assumptions, if the submarine were not found in the first survey, then a second survey of the same grid square, as denoted in Equation (3), will yield a secondary posterior probability of approximately 4.2%. Taken together, 4.2% represents the chances of success in finding the submarine in the given grid square in a second sweep.

Bayesian strategies are a staple of operations analysis search theory. For instance, the U.S Coast Guard incorporates Bayesian search strategies into its Search and Rescue Optimal Planning System (SAROPS).8 Successful outcomes produced by Bayesian search strategies have led to a general consensus on the technique’s utility. Identification of the underwater wreckage site of Air France Flight AF 477 underscored this utility. In the 2011 discovery, investigators created probability density functions (PDFs) from weighted scenarios supplemented by anterior knowledge of nine commercial aircraft accidents, known flight dynamics, and final trajectories.9 These PDFs drew search boxes that broadened until a Brazilian corvette recovered components of AF 477 buoyed on the surface.

Stern view of the nuclear-powered attack submarine USS Scorpion (SSN-589) showing the upper portion of the rudder (with draft markings) and the port stern plane. Note that the after portion of the engine room section (has been) telescoped into the machinery room. The ribs of the stern planes can be seen due to the deformation of the metal covering them. (Official U.S. Navy Photograph, from the collections of the Naval History and Heritage Command.)

However, Bayesian search strategies warrant legitimate criticism for their implicit use of subjective analysis. Terrill and Project Discover’s usage of Bayesian search strategies narrates a story of arbitrary values associated with each scenario. This is seen especially when the researchers place heavy subjective weight on interview data from the few remaining witnesses of a B-24 bomber’s last location.10 Taken together, Bayesian search strategies force analysts to quantify what is essentially qualitative information (e.g., the probability that an elderly man can accurately recall the events of the crash). These limitations create possibilities for higher uncertainty and a wider confidence interval. In addition, Bayesian search strategy can overshadow other powerful methods to form search boxes such as a Gittins index formula.11

2: Implementation of Side-Scanning Sonar for Seabed Imaging

Sonar, otherwise known as sound navigation and ranging, is a method that leverages sound propagation as a way to detect an object’s position and to visualize shapes from acoustic signatures in the form of echoes. The return frequency and radiated noise of an object allow for target acquisition and safe navigation by submarines dependent on the vicinity’s sound velocity profile; for researchers hoping to find inactive submarines, side-scan sonars lend mapping capabilities.

These devices construct images from cross-track slices supplied by continuous conical acoustic beams that reflect from the seafloor—wave emission speed can reach nearly 512 discrete sonar beams at a rate of 40 times a second.12 Data produced by side-scan sonars assembles a sonogram that converts into a digital form for visualization. The utility of side scan sonars is trinitarian; they create effective working images of swaths of sea floor when used in conjunction with bathymetric soundings and sub-bottom profiler data.13 Form factors of side-scan sonars allow the device to be highly mobile and serve as flexible, towable attachments for the tail of any-sized ships, giving liberty to human operators to adjust the directionality of ensonification. In addition, side-scan sonars contain adjustable frequency settings. A change in a side-scan sonar’s frequency will affect the sonar’s emitting wavelength, giving the operator flexibility on target acquisition. Side-scan sonars can operate as low as the 50kHz range to cover maximum seabed area; alternatively, the instrument can operate at 1 MHz for maximum resolution. This feature is extremely vital because submarines alter in length by model and different bodies of water share unique sound velocity profiles. Another advantage with side-scan sonars is their high precision record at sub-meter accuracy level for horizontal planes and at the centimeter-error level for vertical planes.14

Side-scan sonar systems exist as a vital apparatus to any search operation because the alternatives for mapping are minimal. Methods other than side-scan sonars like low-frequency multi-beam bathymetric data scanners, when reappropriated, are imperfect in object identification accuracy and better for scanning large seabed topographic structures like underwater mountains.15 Recent advances in magnetic anomaly detectors16 appear promising for future seabed exploration, but these instruments still require parallel approaches or in-tandem usage with side-scan sonars. Until magnetometers can extend their range beyond identifying magnetic objects in the Epipelagic Zone—the uppermost layer of the ocean where sunlight is still available for photosynthesis—side-scan sonars will be more consistent and versatile than magnetometers.

A mosaic of combined sonar images shows how close the Titan submersible was to the Titanic debris field. The Titan was lost on June 18, 2023. (Graphic via RMS Titanic Inc.)

Deployment of side-scan sonar occurs in the intermediary stage of search operations. A vessel will have a side-scan sonar mounted on or embedded in a towfish. Tethered to the main vessel, the side-scan sonar will perform a proper sonar survey of a proposed area by maintaining a rigid survey line along with a consistent towfish “altitude” when trailing the ship. Technicians carefully check the GPS receiver of the towfish to rectify course deviations, if needed, by manually changing the ship and towfish’s heading. A side-scan sonar operates with a survey mode to capture anomalies, which visual graphs will register and mark for later investigation by an unmanned underwater vehicle (UUV).

Unfortunately, handlers of side-scan sonars will notice several limitations that must be accommodated. A restriction to side-scan sonars is their inability to image directly below side-scan transducers. In other words, ships must compensate for a side-scanner’s blind spot by staggering their mow-the-lawn strategy. In addition, side-scan sonars contain software that prohibits the surpassing of a certain speed limit for towing, lest the receiver show significant scattering, absorption, and incoherent imagery. Like other instruments, side-scan sonars’ physical power consumption can be a variable for constraint.

Lastly, side-scan sonars perform according to the quality of the bathymetric data supplied. By themselves, side-scan sonars cannot efficiently identify changes in gradients and sound velocity profiles in real-time. High frequency/high resolution sonars operate at relatively short ranges via direct path sound propagation, which limits the refraction of sound waves and consequent distortion. This means the side-scan sonar will have a handicap in reporting the propagation paths of its rays and the sound channels, meaning knowledge of shadow zones may be omitted.17 This is a search investigator’s worst nightmare because failure to adequately search a grid may lead to incorrect, permanent marking of a square not holding a target. Imperfect data or simply lack of bathymetry data also contribute to the limitation of side-scan sonars.

3: Integration of Adaptive Unmanned Underwater Vehicles for Forensic Searches.

Since their introduction in the 1960s, UUVs have played a major role in every forensic investigation for a lost submarine. UUVs act as surrogates to human divers who cannot comfortably operate for extended periods of time at depths greater than 100 meters. To illustrate the need for UUVs, the USS Grayback was discovered at a depth of 1,417 feet (431 meters)18 — an impossible depth for divers, but not for the submarine itself. UUVs support forensic scientists in more than just underwater photography. UUVs collect bathymetry data, use ultrasonic imaging, measure strength of ocean currents, and detect foreign objects by their inertial or magnetic properties. Variants of UUVs are categorized into two robotic classes: remotely operated underwater vehicles (ROVs) and autonomous underwater vehicles (AUVs). ROVs allow for direct piloting by a human operator from a remote location with signal. AUVs function independently and follow pre-programmed behavioral search patterns.

A photo taken by a remotely operated vehicle (ROV) shows the sunken Indonesian Navy submarine KRI Nanggala-402 in Denpasar, Bali, Indonesia, May 18, 2021. KRI Nanggala-402 was lost on April 20, 2021. (Indonesian Navy photo)

The UUV variant, Remus 100,19 manufactured by Woods Hole Oceanographic Institute, deceptively resembles a torpedo, but functions as an effective explosive ordnance disposal detection device for the Navy. When refitted for search operations, the Remus (AUV) variant can perform dual-frequency side-scan sonar operations in independent mow-the-lawn search sequences.20 The Remus’ transponder wields GPS and doppler velocity logs that have proven to be more accurate in measurements than earlier AUVs. Customarily, forensic actors will deploy ROVs and AUVs for close-up identification or routine investigation of an anomaly, instead of wide-area search missions. These ROVs display high-definition, colorized video feeds for operators on a vessel; the latency between pilots and the ROV ranges from one to two seconds, making for fast time on responsive decisions.

Conclusion

This analysis examines a trinity of contemporary methods revolving around statistics and autonomous vehicles that aid officials in search and rescue operations for submarines. Corporations and officials should note that innovating and constructing more effective models in search operation becomes worthwhile when speed determines the ability to save lives. While this analysis discusses the employment of the aforementioned technology in the context of submarines, these methods can be theoretically implemented for other maritime interests: finding missing planes, undertaking the historical preservation of shipwreck sites, and embarking on deep-sea mining. For all these reasons, the U.S. has an inherent stake in advancing a discussion about progress in submarine search and rescue tactics.

Andrew Song is a U.S. Navy Nuclear Submarine Officer. His previous publications have appeared in The Wall Street Journal, The National Interest, Military Review, Journal of Indo-Pacific Affairs, and ProceedingsHe graduated with a B.A. in Global Affairs from Yale University in 2022.

References

1 Amos, Jonathan. “One-Fifth of Earth’s Ocean Floor Is Now Mapped.” BBC News. BBC, June 20, 2020. https://www.bbc.com/news/science-environment-53119686.

2 “DOS Involved in the Finding of the French Submarine La Minerve.” Deep Ocean Search, October 3, 2019. http://www.deepoceansearch.com/2019/10/03/dos-involved-in-the-finding-of-the-french-submarine-la-minerve/.

3 Fenning, P. J., Donnelly, L. J., 2004. Geophysical techniques for forensic investigation. Geological Society of London Special Publications, 232, 11-20.

4 Elfrink, Tim. “A WWII Submarine Went Missing for 75 Years. High-Tech Undersea Drones Solved the Mystery.” The Washington Post. WP Company, November 11, 2019. https://www.washingtonpost.com/nation/2019/11/11/uss-grayback-discovered-tim-taylor-lost-project/.

5 Ibid.

6 L.D. Stone, “Operations Analysis during the Underwater Search for Scorpion” Naval Research Logistics Quarterly, vol. 18(2), pp. 141–157. 1971

7 Terrill, E., Moline, M., Scannon, P., Gallimore, E., Shramek, T., Nager, A., Anderson, M. (2017). Project Recover: Extending the Applications of Unmanned Platforms and Autonomy to Support Underwater MIA Searches. Oceanography, 30(2), 150-159. Retrieved March 1, 2021, from http://www.jstor.org/stable/26201864

8 Stone, L. (2011). Operations Research Helps Locate the Underwater Wreckage of Air France Flight AF 447. Phalanx, 44(4), 21-27. Retrieved March 2, 2021, http://www.jstor.org/stable/24910970

9 Soza & Company, Ltd. (1996). The Theory of Search: A Simplified Explanation: U.S. Coast Guard. Contract Number: DTCG23-95-D-HMS026. Retrieved on 2010-07-18 from http://cgauxsurfaceops.us/documents/TheTheoryofSearch.pdf

10 Terrill, E. “Project Recover.” Oceanography 2017.

11 Weitzman, Martin L. (1979). “Optimal Search for the Best Alternative”. Econometrica. 47 (3): 641–654.

12 “Side Scan Sonar.” Exploration Tools: Side Scan Sonar: NOAA Office of Ocean Exploration and Research, 2002. https://oceanexplorer.noaa.gov/technology/sonar/side-scan.html.

13 Jean M. Audibert, Jun Huang. Chapter 16 Geophysical and Geotechnical Design, Handbook of Offshore Engineering, Elsevier, 2005. ISBN 9780080443812, https://doi.org/10.1016/B978-0-08-044381-2.50023-0.

14 Aaron Micallef. Chapter 13: Marine Geomorphology: Geomorphological Mapping and the Study of Submarine Landslides, Development in Earth Surface Processes, Elsevier, Vol 15, 2011, pg 377-395 ISBN 9780444534460, https://doi.org/10.1016/B978-0-444-53446-0.00013-6 (https://www.sciencedirect.com/science/article/pii/B9780444534460000136)

15 Elfrink, “A WWII Submarine went Missing” The Washington Post. 2019.

16 Geophysical Surveying Using Magnetics Methods, January 16, 2004, University of Calgary https://web.archive.org/web/20050310171755/http://www.geo.ucalgary.ca/~wu/Goph547/CSM_MagNotes.pdf

17 “Side Scan Sonar.” United States Naval Academy , February 1, 2018. https://www.usna.edu/Users/oceano/pguth/md_help/geology_course/side_scan_sonar.htm. (2) Sonar Propagation. Department of Defense . Accessed April 7, 2021. https://fas.org/man/dod-101/navy/docs/es310/SNR_PROP/snr_prop.htm.

18 Elfrink, “A WWII Submarine went Missing” The Washington Post. 2019.

19 REMUS”. Woods Hole Oceanographic Institution. https://www.whoi.edu/what-we-do/explore/underwater-vehicles/auvs/remus/

20 J. Ousingsawat and M. G. Earl, “Modified Lawn-Mower Search Pattern for Areas Comprised of Weighted Regions,” 2007 American Control Conference, New York, NY, USA, 2007, pp. 918-923, doi: 10.1109/ACC.2007.4282850.

Featured Image: August 1986 – A view of the detached sail of the nuclear-powered attack submarine USS Scorpion (SSN-589) laying on the ocean floor. The starboard fairwater plane is visible protruding from the sail. Masts are visible extending from the top of the sail (located at the lower portion of the photograph). A large segment of the after section of the sail, including the deck access hatch, is missing. (Official U.S. Navy photograph)

Focus on the Fundamentals: The Siren Song of Technology in Maritime Security

By Jamie Jones and Ian Ralby

What good is the world’s most advanced “dark targeting” platform to uncover previously untraceable vessels if the local navy, coast guard, or marine police cannot stop the crime?

Instead of being wooed by “game-changing” technologies, maritime security professionals should focus on ensuring their organizations can perform critical functions first. Similarly, professionals who partner with chronically under-resourced organizations should focus on assisting with basic functions instead of dangling “silver bullets” that promise to solve all their woes.

The Problem

The maritime security sector is under a constant barrage of hype about “game-changing” technology, particularly when it comes to maritime domain awareness (MDA). Maritime domain awareness is the effective understanding of anything associated with the maritime domain that could impact security, safety, the economy, or the marine environment. Several technological platforms are purported to “revolutionize” MDA with the promise of significantly improving countries’ abilities to govern their waters. Prominent examples include synthetic aperture radar (SAR), radio frequency identification (RFID), electro-optical (EO) satellite imagery, and artificial intelligence (AI) algorithms that use data from the Automatic Identification System (AIS) to evaluate vessels’ historical actions and predict future behavior. One company purports to be able to “quickly develop machine learning models to solve problems taking place in the vastness of the world’s oceans.” Similarly, new satellite-based technology supplied by the Quad (the United States, Australia, India, and Japan) is expected to help smaller island nations govern their waters.

Being able to watch bad actors on the water is not the same as being able to do anything to stop them. By itself, MDA has little deterrent effect: the waters will still be ungoverned if a country has no way to legally or operationally act upon what it sees. While new MDA technology can be exciting, the siren song of “shiny new toys” risks confusing maritime voyeurism with more assertive and effective action. For many countries, simply watching bad actors harm without the ability to stop them is frustrating. The constant stream of new—but sometimes proprietary or otherwise incompatible—technology can even create a disincentive to act and enable policy procrastination. Some policymakers want the equivalent of closed caption television on the water before they are willing to take action against problems like human trafficking, illegal fishing, and smuggling of drugs and weapons.

Before jumping to advanced technology, it is vital to be able to rigorously and systematically analyze MDA data from any source; have a repeatable, documentable mechanism for sharing that analysis with operators who can act on it promptly; have the capacity to plan and execute interdiction operations in a manner that also collects and preserves evidence; have a well-defined process for handing a maritime case over to the land-based authorities; and, ultimately pursue a legal finish that includes a penalty commensurate with the offense.

Man in the Loop

MDA technology cannot supplant humans; most Maritime Operations Centers (MOCs) run by militaries and law enforcement agencies employ several MDA analysts round-the-clock. These experts are needed to interpret what they see and then communicate their analysis to authorities who can act on this information and knowledge. In countries that lack funding or technical infrastructure for flashy MDA platforms, humans are even more important to the maritime security equation.

A well-trained analyst can, and must, perform functions that technology cannot. For example, to understand what might be happening in the water, the analyst must understand what should be happening. Understanding this context requires knowledge of local customs and culture, knowledge of a particular area’s fishing patterns, shipping routes, the effects of weather, seasonal dynamics, and knowledge of what is “normal” for that area. Indeed, relying only on technology may give the country a false sense of security, seeing some of what is happening in its waters without an in-depth understanding of the context.

Analysts must also be trained in maritime enforcement jurisdiction so they can understand what activities the country can pursue in each of the maritime zones their country has claimed.

Perfect Awareness is Useless without Action

The latest MDA technology often comes with a hefty price tag. Synthetic Aperture Radar capability, for example, is expensive and even analysts who are skilled at using other MDA sources cannot simply look at the blurry images of what amounts to satellite-based radar and make sense of it. That said, a suitably trained analyst looking at such radar captures in combination with other technology to correlate it to AIS data can help gain a clearer understanding of what is happening at sea. But this means that the expensive SAR data has to be paired with other expensive technology and a well-trained analyst for it to be of value. Even if these systems are provided cost-free, and analysts can translate the data into a useful understanding of actionable anomalies, interdictions still cannot occur without vessels on the water.

With initiatives such as the Australian and Japanese Patrol Boat programs, numerous developing nations now have access to vessels well-suited for patrolling their waters. These vessels, however, require well-trained crews, along with funding for fuel and maintenance to make them useful. In some countries, the government’s entire maritime force is required just to operate the vessel, which understandably discourages the frequency of its use. Access to parts, maintenance, fuel, and provisions conspire to keep these vessels pier side. Consistent funding and training for crews and boarding officers to interdict suspect vessels are necessary.

Though not as alluring as slick MDA technology, funding for the basic needs required to patrol waters should be prioritized over new technologies. Without basic operational capacity and capability, no amount of MDA will make a country’s waters safer, more secure, more stable, or more prosperous.

The other component to action besides “boots on deck” is the legal finish or the successful adjudication of a maritime offense. Indeed, a meaningful penalization through an adjudicative process is often the only effective deterrent to criminal activity in a country’s waters.

Behind a properly trained and funded boarding team are investigators trained in maritime cases. The investigators are critical to putting together a prosecutable case. Furthermore, prosecutors must be well-versed and well-trained in maritime law to successfully prosecute maritime crimes. And finally, the law itself must be fit for purpose, addressing the full spectrum of maritime offenses that are being pursued by criminal actors in the country’s waters.

The legal finish requires human resources. Human resources planning is difficult: it takes time to plan how many operations the country may need to conduct each year, and how many people need to be in place and trained to enable said operations. It requires recruiting the right people, funding their training, and then also a plan for retaining them once they are trained. Indeed, human resources are a significant, but necessary investment. Planning and funding for human resources may not sound as glamorous as showcasing the latest drone or artificial intelligence platform. But without human resources, the technology leaves the State’s deterrent capabilities impotent.

Conclusion

Flashy new technologies can be fun to play with, and some are truly useful. Still, they are only part of the equation for providing maritime security, and not necessarily the most important. To be useful, these tools must be paired with institutional capacity to analyze data, share information, plan and execute operations, collect evidence, handover to land authorities, conduct investigations, prosecute, adjudicate, penalize, and, when necessary, both legislate and regulate to account for changes in the security environment. Indeed, it is healthy and helpful to be skeptical of how much any technology will “solve” problems that require human expertise and human responses to be wielded effectively. It behooves those with meager budgets, and those trying to help partners with meager budgets, to focus funding and attention on building the skills and institutions needed to use the MDA technology that is already available, as well as whatever the future may hold. Every State should strive for maximum efficiency, effectiveness, and impact regarding maritime security concerns it can already see before pursuing a heightened visibility that may leave it watching bad actors without the wherewithal to stop them. 

Jamie Jones is a legal institutional capacity-building attorney with the Defense Institute of International Legal Studies (DIILS) focusing on maritime security in the Pacific Island Nations. She earned her undergraduate degree in agriculture from Kansas State University, a master’s degree in national security and strategic studies from the U.S. Naval War College, and her law degree from Washburn University’s School of Law. 

Dr. Ian Ralby is a recognized expert in maritime and resource security. He has worked in more than 95 countries around the world, often assisting them with developing their maritime domain awareness capacity. He holds a JD from William & Mary and a PhD from the University of Cambridge. 

The views presented in this article are the author’s own and do not necessarily represent the views of any other organization.

Featured Image: The ship Xin Lian Yun Gang seen in the Port of Rotterdam. (Photo via Wikimedia Commons)

A Russian Lake: Has the West Ceded the Black Sea to Russia?

By Charles P. (Chuck) Ridgway, Jr.

In 2016, Turkish President Recep Tayyip Erdoğan called the Black Sea a “Russian Lake” and encouraged NATO to do more to counter Russia’s efforts to exert control over it.1 Never was that control shown to be more complete than last August, when the Russian Federation Navy stopped and boarded Palau-flagged freighter Şükrü Okan in the southwest portion of the Black Sea, about as far from the Russian coast as you can get, delaying its journey and menacing its crew at gunpoint before determining that it was not carrying contraband and allowing it to proceed. This incident may be seen as the canary in the coalmine indicating imminent suffocation of freedom of navigation in the Black Sea.

The Need for Sea Control

Much has been made of Ukraine’s successful and impressive efforts at sea denial, forcing the Russian Black Sea Fleet to stay well out of coastal missile range and even destroying major units in their homeports as well as at sea. But in what is quite obviously a largely maritime war,2 Russia appears to be achieving its strategic aims despite these tactical setbacks. The Sea of Azov is completely controlled by Russia and a look at MarineTraffic shows that few vessels dare come within 100 nm of Odessa. While the boarding cannot be said to have taken place as part of a blockade, since Russia has not formally declared a blockade, only issued various warning areas3 and vague threats about targeting ships across the Black Sea,4 and is not attempting to enforce a blockade in the manner prescribed by international law, it is telling that the boarding took place where it did, putting the world on notice that ships anywhere in the Black Sea even vaguely suspected of heading towards Ukraine may be boarded, and possibly seized or sunk. While at the same time, President Putin protests when a US warship calls at Istanbul.5 For all intents and purposes, there exists a de facto long-distance blockade, for no other word adequately describes what Russia is doing in the Black Sea. This blockade’s legality may be questionable at best,6 but its effectiveness cannot be doubted. NATO nations, as well as the rest of the world interested in freedom of navigation—including, seemingly, Palau—are doing little to challenge this situation, effectively ceding the maritime domain of the Black Sea to Russia’s bullying and bluster. It seems the Black Sea has indeed become a Russian lake.

The international law of naval warfare covering belligerent interference with merchant shipping, such as blockades and the prevention of the carrying of war contraband, has always represented a compromise between the objectives of the belligerent and the harm neutrals are willing to absorb in losing a certain amount of freedom of navigation.7 The US Military Academy’s Lieber Institute for Law and Warfare has pointed out that the boarding of the Şükrü Okan was legal under “Belligerent Right of Visit and Search.”8 On the other hand, Russia is a signatory to UNCLOS and there are no circumstances permitted by UNCLOS where this boarding could be said to fall under the right of visit of warships. In boarding Şükrü Okan, the Russian navy clearly violated the terms of UNLCOS to which it is bound.

Admittedly, UNLCOS does not address any aspect of naval conflict. But can interference with freedom of the seas be considered legal when the war under which the boarding was conducted is both undeclared and itself illegal? Does UNCLOS cease to apply because one signatory decides to lay mines or stop by force another country’s merchant ships? Are neutral nations willing to accept that UNCLOS can be suspended unilaterally and without formal warning? Most countries, especially those that adhere to the principle of Qualified Neutrality,9 should tend to think not. If the world stands by and does nothing, then Russia’s actions become the new status quo, UNCLOS loses much of its meaning, and the Black Sea—along with any other maritime region where the world persistently acquiesces in the face of aggression—risks losing its status as an international body of water.

With the collapse of the Black Sea Grain Initiative last summer, Ukraine created the “Ukraine Humanitarian Grain Corridor” by which ships transit through the territorial waters of Bulgaria and Romania, and mainly use Ukrainian ports on the Danube to load grain. The corridor has allowed a certain number of ships to carry grain out of the Black Sea over the past few months,10 though questions remain about the sustainability of insurance costs, especially after a Liberian-flagged vessel was hit by a Russian missile in Odessa on November 9, 2023.11

Grain shipping routes in the aftermath of the Ukraine invasion. (Graphic via BBC, based on United Nations data)

While Ukraine’s national bank has recently brokered a deal through Lloyd’s of London and other insurers to cut costs12 and many are calling the corridor successful, reports indicate that the grain exported is just a fraction of pre-war quantities: 700,000 tons from August to the end of October versus around 6 million tons a month before the Russian invasion.13 By December, a total of 200 ships had used the corridor carrying an estimated 5 millions tons of agricultural product14 — still well short of prewar levels. From a more strategic viewpoint, the fact remains that in order to export even this amount of grain, merchant ships must hug NATO nations’ coasts, reinforcing the point that the international waters of this part of the Black Sea are not open to shipping. If the shipping industry is unwilling to use the international route, can it still be considered international?

This situation brings up two interesting and related questions: What can be learned from this? And, what can be done about it?

Some Notable Lessons

The first thing that becomes apparent is that sea denial is insufficient when a country depends on open sea-lanes for its basic economic livelihood. While nearly all nations are dependent on the sea for their economic wellbeing, Ukraine’s dependence is stronger than most. A significant portion of its economy rides on its ability to export its grain. And the only efficient, indeed feasible, way to export the majority of it is by ocean-going cargo vessels transiting the Black Sea.

Ukraine’s sea denial efforts offer no help in escorting these vessels or otherwise reducing the perceived risk and, in some ways have enhanced it. Pushing the Russian Black Sea Fleet out of the immediate environs of the Ukrainian coast has had the odd effect of causing Russia’s blockade to expand from a close blockade to one that covers essentially the entire Black Sea minus the territorial waters of the three NATO nations there. And laying defensive mines might have prevented a Russian amphibious assault on Odessa, but has added to the perceived risk to shipping while also allowing political cover for Russia to lay its own mines.

Second, a flag of convenience is no more than that: convenient, until it no longer is. After the Şükrü Okan incident in August, Türkiye waited several days before issuing a warning to Moscow about the boarding of the Turkish-owned and operated ship, with President Erdoğan stating that it was a matter for the flag state.15 An important duty of a flag state is to provide security to vessels on its registry and represent vessel owners’ interests in freedom of the seas on the international stage. Except for a few brief and very localized exceptions, this has not been an important consideration since the end of World War II, though Houthi actions in the southern Red Sea seem to be changing this calculus. None of the world’s leading flag states of convenience—not Liberia, Panama, Marshall Islands, or even Malta—are in much of a position to actively defend their merchant vessels, or even to apply any meaningful diplomatic pressure on a state aggressor as Russia has become in the Black Sea. It is not likely that President Putin will bat an eye at a protest filed by Palau in either the International Maritime Organization (IMO) or UN General Assembly. It is equally unlikely that the Russian Federation Navy would have chosen to board a ship flagged to a NATO member nation or, say, China at this stage of the conflict. Since vessel owners and operators, like the Turkish owners of the Şükrü Okan, cannot count on the support of their own governments when they choose a flag of convenience, it will be interesting to see if they, as the conflict at sea continues, or even expands, reconsider their choice of flag, perhaps preferring one with the naval and diplomatic might to protect their ships.

Third, a blockade no longer requires “effective enforcement”16 to be effective. Apparently, a single boarding, in which the boarded vessel was allowed to proceed, coupled with a few floating mines, is enough to warn off other neutral ships from heading to Ukraine, thereby allowing Russia’s “distant blockade” to expand across the entire Black Sea even while much of the Black Sea Fleet is now holed up in Novorossiysk. It may be a “paper blockade” but that seems to be enough in this conflict.

Fourth, the reason such limited means can produce so effective a blockade is that insurance considerations drive risk assessments in shipping. This is especially true in the Black Sea. Increased war risk premiums during the heyday of Somali piracy did not greatly affect traffic through the Gulf of Aden for a variety of reasons, mainly that relatively few ships of the total traffic through the area were actually attacked and there was no economically alternative route. Instead, the shipping industry and the international community adapted their behavior to increase security and deter attacks. During World War II, though merchant crews obviously faced great physical risk, governments assumed almost all the financial risk for ship and cargo loss (many of the ships and most of the cargo being government owned). The calculus appears to be different in the Black Sea: shipping grain does not offer a profit substantial enough to offset the war risk costs, maritime trade union concerns, and potential losses to either seizure or sinking. Merchant ship operators will begin carrying large quantities of Ukrainian grain when it again becomes profitable.

April 10, 2023 – Bulk carrier ARGO I docked at the grain terminal of the port of Odessa, Ukraine. (Photo via Bo Amstrup/AFP/Ritzau Scanpix)

Finally, the key to pushing Russian control of the Black Sea back towards the Russian coast lies with Türkiye. In the first place, Türkiye is a naval power in its own right and, should it come to it, is fully capable of taking on the Russian Black Sea fleet on more than equal terms. The Turkish fleet is in the best position to reassert control over, at the very least, the southern Black Sea including, for lack of a better demarcation, Türkiye’s EEZ17, and it is Türkiye, as a maritime nation, that has the greatest direct interest in doing so. Second, Türkiye’s control of the entrance to the Black Sea makes it the most important partner for those nations who wish to increase non-Black Sea naval presence there. In recognizing this, one must also recognize that the Montreux Convention, as it currently stands, serves Türkiye’s interests and Türkiye is unlikely to want to renegotiate it: any actions by non-Black Sea states will have to be in accordance with Montreux. Third, Türkiye, more than any other NATO Nation, has both working diplomatic relationships and economic ties (such as TURKSTREAM) with Russia that could allow for useful dialog with respect to Black Sea maritime control but which could also complicate such dialog.

The Way Ahead

Is there anything to be done about this situation? A variety of suggestions have been made, from establishing convoys of merchants ships through the blockade—and mine-infested—zone escorted by NATO’s Standing Naval Forces, to getting Russia to end the conflict. The former suggestion was soundly refuted by RUSI18 on the grounds that the economic/insurance considerations, the Montreux convention, and the nature of the current threat would make such escort impracticable to maintain and not very effective; the latter is clearly a pipedream—until Russia is ready to end the conflict, whether because Russia has achieved all its aims or because it has been defeated, the conflict will go on. So the question really becomes, what constraints is the rest of the world willing to accept on freedom of navigation in the Black Sea and what can they do to push back against the ones they don’t accept.

Here are some practical suggestions, arranged more or less from least to most provocative to Russia, and thereby in order of what would take the most backbone to implement.

First, improve maritime domain awareness (MDA) of the region. A September symposium in Greece highlighted the deficiencies in Black Sea MDA.19 While it is highly probable that no Russian surface ship or submarine of the Baltic fleet gets underway without being actively tracked by one or more NATO nations, and the same is likely true in most cases for the Northern fleet, this probably cannot be said for Black Sea assets. When a Black Sea Fleet Kilo-class submarine leaves Sevastopol and submerges, it is most likely immediately lost to sight until it returns. Improved MDA would allow for greater analysis of trends and recognition of changes in the situation sooner, such as new threats (recently laid mines) or evolution of broader diplomatic conditions (e.g. identifying what changed to make Russia no longer want to participate in the grain deal). It would also allow for better enforcement of sanctions on Russian oil, tracking of individuals of interest, and detection of Russian gray zone maritime operations.

Second, maritime air patrol should be enhanced. There is a significant shortfall of MPA assets and actual patrols over the Black Sea. Of the NATO Black Sea nations, only Türkiye has an MPA component. NATO AWACS aircraft have been reported operating over Poland along the Ukrainian border but not over the Black Sea. There is also reporting that US MPA aircraft are conducting missions over the Black Sea, but it is not clear with whom the information gathered is being shared.20 More MPA coverage would contribute to freedom of navigation, enhanced MDA, intelligence collection, and order of battle development.

Third, governments interested in supporting Ukraine’s ability to export grain should subsidize war risk costs. While subsidies to shipping to offset increased insurance and other war risk costs would not reduce the physical risk to crews or ships, they could make the carrying of Ukrainian grain more attractive. With the end of the Black Sea Grain Initiative, Ukraine began offering subsidies for this purpose but it remains to be seen if this, combined with the new Lloyd’s deal, will be enough to offset costs adequately or if it will be financially sustainable for Ukraine or the insurers over the long term.21

Fourth, ship owners should consider reflagging their grain ships to registries that can offer naval protection and diplomatic gravitas. Palau, like Liberia or Panama, may not be in a position to impede Russian interference with ships of their registry, but all NATO nations are. Russia would need to be willing to risk significant escalation if it wanted to board, say, a German-flagged bulk carrier 30 miles out from the Istanbul Straight. It is not necessary to escort merchant ships—and probably not particularly effective as long as the main threat remains mines22—when the flag carries the weight of Article V with it. It may even be worth considering employing (appropriately-flagged) government-owned ships in the trade, which could also contribute to avoiding war risk costs.

Ship operators should harden merchant ships to prevent boardings. The world’s maritime polity learned a great deal about preventing boardings during the days of Somali piracy and many of the steps developed under “Best Management Practices”23 would serve equally well in repelling unwanted boardings in the Black Sea. Shipping operators or flag states may even wish to embark security teams, generally considered the most effective means at preventing piracy attacks. It is highly unlikely ship owners would choose to do this, but the possibility that a boarding could be opposed would force Russia to determine how far they want to go the next time they attempt a boarding. Is the Russian Navy really willing to sink a neutral flagged merchant ship with naval gunfire?

Navies should be conducting freedom of navigation operations (FONOPS) in the Black Sea. Neutral nation warships, and especially NATO Nation warships, whether under NATO or national operational control, should be operating and patrolling in all the international waters of the Black Sea. There is no legal or diplomatic reason why a group of neutral frigates should not be conducting routine exercises 20 nautical miles off Novorossiysk or shadowing every Russian Federation Navy ship that leaves Russian territorial waters. While the three Black Sea NATO nations are fully capable of this,24 the diplomatic effect would be greater if there were non-Black Sea-based ships involved, even if just a token and occasional involvement. Diplomatic work with Türkiye should focus on allowing non-belligerent warships into the Black Sea in accordance with Montreux for this purpose. FONOPS is a much better use of surface assets than convoy escort given current conditions in the Black Sea. Aircraft can do FONOPS too.

And, obviously something will need to be done about mines. The recent agreement among the Bulgaria, Romania, and Türkiye to create a mine-countermeasures task group is welcome news on this front.25

Many would argue that these steps are provocative and risk escalating the conflict in Ukraine.26 No one wants a World War III, but the simple fact is that it is up to Russia whether or not to start one by firing on NATO warships, or NATO nation-flagged merchant vessels. Excessive worry about provocation should not hinder warships of neutral or non-belligerent nations from operating wherever in international waters their governments should wish or from ensuring the free flow of goods to the world’s markets in accordance with established international law. Operating in international waters is no more an act of aggression than it is to walk down a dangerous alley at night ready for the worst. Such operations may well complicate operational freedom of movement and rules of engagement for the Russian Black Sea Fleet, for surely they wish to avoid unintended escalation as well, but not conducting them simply makes it excessively easy for Russia not to have to account for such possibilities in planning and executing its naval operations. And there is no reason to make it easy for Russia—especially when doing so cedes effective control over this important maritime space and hurts the world’s economy.

But principle is an even stronger argument for wresting back maritime dominance in the Black Sea from Russia: the principle of freedom of the seas, of the free flow of goods, and of the schoolyard principle that a bully shouldn’t be allowed to get away with it. And, of course, the principle of sea power. Every violation of UNCLOS, every loss of international access to any body of water, every impediment by force of arms to free trade hurts the sovereignty of other nations and chips away at the post-war international order that benefits the free countries of the world. The reason navies exist is to keep the seas open for the benefit of their citizens, but navies have to be willing to go into harm’s way to do so. For all of history, from the Peloponnesian War, through both world wars, to the Falklands conflict, war has been decided by sea power. The Ukraine War is no different. Russia appears to recognize this. Will the rest of the world?

Chuck Ridgway is a retired US Navy surface warfare and reserve Africa foreign area officer. After leaving active duty, he worked for ten years as a NATO international civilian at the NATO Joint Analysis and Lessons Learned Centre in Portugal. Since then he has consulted with a variety of organizations, including One Earth Future Foundation’s Oceans Beyond Piracy and Stable Seas programs, the United Nation Office of Drugs and Crime’s Global Maritime Crime Program, and the US Defense Security Cooperation Agency’s Institute for Security Governance. A native of Colorado, he lives in Denver. This is his first piece for CIMSEC.

References

1. https://eurasianet.org/erdogan-plea-nato-says-black-sea-has-become-russian-lake

2. Midrats Podcast, Episode 662: Grain, Oil and the Unfreeing of the Seas, 23 July 2023

3. https://www.nato.int/cps/en/natohq/news_217835.htm

4. https://www.lloydslist.com/LL1145965/Russia-warns-that-ships-heading-to-Ukraine-are-now-a-military-target

5. https://www.stripes.com/branches/navy/2023-08-21/black-sea-russia-ukraine-turkey-us-navy-11114380.html

6. See Fraunces, M. G. (1992). The International Law of Blockade: New Guiding Principles in Contemporary State Practice. The Yale Law Journal, 101(4), 893–918, and https://lieber.westpoint.edu/russia-ukraine-war-naval-blockades-visit-search-targeting-war-sustaining-objects/ for discussions of the legal principles of modern blockades and an interpretation of Russia’s blockade of Ukraine.

7. It is debatable if NATO Nations can be considered strictly neutral in the Ukraine conflict, given that nearly all of them are providing war material to one of the belligerents.

8. https://lieber.westpoint.edu/russia-ukraine-war-naval-blockades-visit-search-targeting-war-sustaining-objects/

9. Commander’s Handbook on the Law of the Sea, § 7.2.1 (https://usnwc.libguides.com/ld.php?content_id=66281931)

10. https://www.reuters.com/world/europe/ukraine-alternative-black-sea-export-corridor-is-working-despite-attack-2023-11-09/

11. https://apnews.com/article/russia-ukraine-war-freighter-odesa-9f87d96cc6064094463fd2ecb0828b36

12. https://www.reuters.com/business/marsh-lloyds-launch-ukraine-war-risk-ship-insurance-cut-grain-costs-2023-11-15/

13. https://www.usnews.com/news/world/articles/2023-10-26/ukraine-suspends-new-black-sea-grain-corridor-due-to-threat-from-russian-warplanes-consultancy

14. https://maritime-executive.com/article/ukraine-marks-shipping-milestone-as-imo-pledges-more-assistance

15. https://www.arabnews.com/node/2356936/middle-east and https://turkishminute.com/2023/08/18/analysis-putin-navigated-dangerous-water-test-turkey-red-line/

16. Fraunces, M. G. (1992), page 897.

17. https://www.un.org/depts/los/LEGISLATIONANDTREATIES/PDFFILES/TREATIES/RUS-TUR1987EZ.PDF

18. https://rusi.org/explore-our-research/publications/commentary/how-can-nato-overcome-russias-black-sea-blockade

19. https://geetha.mil.gr/diexagogi-synedrioy-maritime-domain-awareness-in-the-black-sea-sto-kenap-nmiotc/

20. US Navy P-8As are evidently “providing security” to vessels using the Ukraine Grain Corridor (https://www.i24news.tv/en/news/ukraine-conflict/1690835345-ship-sailing-from-israel-becomes-the-first-to-break-russia-s-grain-blockade) and there is reporting that they have also provided targeting information to Ukrainian forces (https://news.usni.org/2022/05/05/warship-moskva-was-blind-to-ukrainian-missile-attack-analysis-shows)

21. UATV Report: “Russia’s Grain Manipulations Failed: Ukraine’s Grain Corridor Resumed Operating Despite Threat”; https://www.youtube.com/watch?v=YLY9-k96CuU

22. If Kalibr missiles start flying into the sides of merchant ships at sea, the need for escorts obviously changes, as would many other aspects of this conflict.

23. https://www.ics-shipping.org/publication/bmp5/#:~:text=Piracy%2Dspecific%20Best%20Management%20Practice,and%20other%20maritime%20security%20threats.

24. Information on where the Turkish Navy operates, in what strength, and if these patrols contribute to NATO-wide MDA, intelligence collection or deterrence is not publicly available.

25. https://www.tagesschau.de/ausland/europa/seeminen-schwarzes-meer-100.html

26. Some, but not all, of these steps may be included in the U.S. State Department’s work on a Black Sea security strategy. For example, in testimony before the U.S. Senate Subcommittee on Europe and Regional Security Cooperation, James O’Brien, U.S. Assistant Secretary, European and Eurasian Affairs, stated that enhanced maritime air patrol had not been considered (https://www.foreign.senate.gov/hearings/assessing-the-department-of-states-strategy-for-security-in-the-black-sea-region). Publicly available information on this strategy and other efforts directed by the Black Sea Security Act (2024 U.S. National Defense Authorization Act § 1247) is still too vague to allow speculation on what specific actions could be taken.

Red Dragon Rising? Insights from a Decade of China Conflict Studies and Wargames

By Robert Kitchen

Introduction

China and the United States see each other as the pacing challenge,1 with Taiwan the obvious potential flashpoint. Correspondingly, different governments and think tanks repeatedly featured the Taiwan conflict in wargames. However, results from these studies varied significantly, ranging from swift Taiwanese capitulation and pyrrhic United States victories to bloody Chinese failures. This review compares several studies, explaining differences in the objectives, outcomes, and implications. As such, it is the first review to collate findings from a broad sample of wargames held over eight years between 2016 and 2023. It identifies a clear, regressive trend in the United States and Taiwanese chances of victory over the period and crucial factors influencing the outcomes for the People’s Liberation Army, the Republic of China, the United States, and allied forces. It concludes with recommendations for future wargame iterations.

Scope

This review focuses on published United States military rather than economic or non-kinetic influence studies. These studies were unclassified or substantively reported in open sources and addressed a conflict in the Western Pacific, usually involving Taiwan and the United States. However, similar studies were undertaken in China, Japan, and Taiwan, which have established military wargaming capabilities.2 The United Kingdom also has wargaming and net assessment capabilities.3 While this paper looks at published studies, it also includes officially announced insights about classified ones.

For comparison purposes, this review groups studies into three discrete eras: before 2017, 2017 to before Russia’s large-scale invasion of Ukraine in February 2022, and those conducted afterward. The timeframes were chosen as they represent three distinct trends. Pre-2018, wargames tended to end favorably for the United States, Taiwan, and allies, albeit at great cost. Between 2018 and February 2022, outcomes grew increasingly pessimistic for the United States and Taiwan, with only one victory, four losses, and two stalemates. Finally, in the two games since February 22nd, 2022, the immediate insights from the larger Russian invasion of Ukraine have tilted the outcomes towards the defender.

Each era is divided into three sections. ‘Overview of studies’ briefly summarizes outcomes and recommendations. ‘Insights and analysis’ provide an overview of trends, differences, and future areas for study. ‘Conclusions’ provides a focus for future United Kingdom iterations.

Overview of studies

The studies table summarizes a range of twelve wargames across three distinct timeframes: three from pre-2018, seven from 2018 to February 2022, and two post-February 2022. Results are color-coded red when China can secure its objectives, yellow when objectives remain contested, and green when China cannot achieve its objectives against the Republic of China, the United States, and other opposition.

Table of studies and wargames.

Studies Before 2017

RAND war with China, 2016.4 This study concerns four general cases of the United States and China’s conventional conflict in the East Asia region, a brief or long duration, and severe versus limited. It examines how specific systems (i.e., aircraft, surface ships, submarines, missiles, command and control) compare against each other. In the 2015 war games, Chinese losses were greater than those of the United States; however, the United States’ losses could be much heavier in a 2025 war.

The report recommended the United States increase interoperability and planning with allies, in part to increase its deterrent posture but also because it recognized that existing weapon stockpiles were insufficient to sustain prolonged campaigns. RAND recommended that the United States improve its ability to sustain protracted conflict to bolster deterrence and invest in more survivable force platforms like submarines and counters for anti-access systems.

RAND Scorecard, 2017.5 This detailed study created a scorecard and periodically examined United States and Chinese military capabilities in ten operational areas. By the last iteration in 2017, the People’s Liberation Army was considered inferior to individual United States capabilities, but its proximity to operations mitigated shortfalls. Based upon then-current trajectories, the United States’ dominance progressively receded over the next fifteen years.

The report suggested that the United States procure bases to improve dispersed redundancy and increase the survivability of aircraft, submarines, and space assets. The report also recommended intensifying diplomatic efforts to secure access to Southeast Asian countries, prioritizing building strategic depth through alliances.

The China Invasion Threat: Taiwan’s Defense and American Strategy in Asia, 2017.6 Ian Easton’s book is still one of the best authorities on Taiwan’s military disposition. Many other studies cite its maps, especially vital beaches, and other assessments. Whilst not a net assessment, Easton lays out many building blocks for one. It also recounts the results of the Republic of China’s military wargames, which Taiwan could hold out in 2017 and 2018 simulations. The book uses primary sources to compellingly lay out the People’s Liberation Army and the Republic of China’s concept of operations, their assumptions, and the likely order of battle. It gives a good account of internal doubts within the People’s Liberation Army and the since lost bullishness of the Republic of China’s military. However, it is prescient regarding the trend in the military balance of power towards China.

The study’s recommendations advocate for the United States to support Taiwan. Still, it makes a compelling case that Taiwan’s position was defensible, and much could go wrong with an attempted invasion. Easton’s look at the captured lessons of the People’s Liberation Army indicates that chief of their concerns is the Republic of China’s long-range strike capabilities and projects to harden the Taiwanese islands, military facilities, and command and control capabilities. Therefore, long-range strike capabilities and infrastructure hardening need reinforcement. The book was relatively silent on preparations for operations other than the full-scale invasion of Taiwan. There were few, if any, lessons on countering People’s Liberation Army pressure campaigns through blockade, air incursions, or diplomatic isolation.

Studies from 2018 to pre-invasion of Ukraine

United States Marines wargame 2019.7 This United States Marine Corps wargame was set in Poland, South Korea, and Taiwan and forced the United States to react to simultaneous crises. Before the start of the game, the sides could invest in emergent capabilities such as artificial intelligence and quantum processing. The United States possessed insufficient forces and logistics to fight and win in all three conflicts simultaneously. Instead, the United States took a Europe-first approach, accepted risk regarding the Republic of China’s ground forces, and attempted to mitigate through naval and air assets. People’s Liberation Army forces were able to land in Taiwan but were unable to subdue the Republic of China and Japanese reinforcements. All theaters ended with local Russian or United States commanders seeking to employ nuclear weapons.

Reported classified Department of Defense (DOD) wargames, October 2020.8 One of the wargames of the series focused exclusively on the United States and People’s Liberation Army forces fighting over Taiwan. The United States Vice Chairman of the Joint Chiefs of Staff commented after the completion that the concentration of combat power for maximum efficiency and effect, and the United States military’s information dominance, is no longer guaranteed. After initial failures, the United States could reverse fortune by testing a new concept known as “expanded maneuver,” which involves the dispersal and disaggregation of combat power across all domains.9 The conclusion was the People’s Liberation Army benefited from extensive study of adversary tactics, techniques, and procedures over the previous two decades and implemented changes that challenged the previous way of war. The Department of Defense is pushing the United States military to adopt the expanded maneuver concept by 2030.

RAND Corporation comments to the media in August and October 2020.10 A RAND Corporation representative asserted that, in wargames set in 2025 and beyond, the United States loses assets in theater very quickly and cannot project power into the battlespace to defeat an invasion. Using multiple airborne and amphibious assaults, the People’s Liberation Army could reinforce a successful lodgement before effective United States assistance arrived.

Another report notes the United States could improve its chances by relying on a new generation of long-range anti-ship missiles combined with space-based reconnaissance. Additionally, using artificial intelligence to locate enemy targets and unmanned undersea drones that can fire torpedoes at the People’s Liberation Army landing craft could further blunt an attack. These capabilities reportedly could be achieved with about five percent of the current Department of Defense’s budget.

Reported United States Air Force wargame, Autumn 2020.11 In this wargame, the United States Air Force repelled a Chinese invasion of Taiwan set in 2030. The Air Force succeeded by using drones as a sensing grid, cargo planes dropping guided munitions, and other novel technologies, but with a large loss of life and equipment. Taiwan also increased defense spending before the conflict, buying drones and electronic warfare equipment. This outcome marked an improvement to similar war games held in 2018 over the South China Sea and Taiwan in 2019. In both those wargames, it ended in catastrophic losses. United States improvements in 2020 effectively deterred the People’s Liberation Army player from launching an invasion. The United States Air Force reportedly needed more and newer tactical aircraft, greater numbers of drones and ‘loyal wingmen’ teamed with crewed aircraft, and more strategic bombers, tankers, and airlift to win a war after 2030.

Center for New American Security Slaughter in the East China Sea, 2020.12 This limited study explored China’s seizure of one of the Senkaku Islands and the Japanese efforts to reclaim them. The United States assisted Japan but with constrained rules of engagement. Both sides sought to contain the crisis, but the conflict escalated nevertheless, culminating with the United States and Japanese forces being unable to reclaim the islands.

Center for New American Security Poison Frog, 2021.13 This study explored the Chinese seizure of Taiwan’s outlying Pratas Islands, which China quickly seized. The United States and its allies found few ways to push China out, without using escalatory military options, while economic and information campaigns failed. Close cooperation between Taiwan, the United States, and Japan could isolate China but did not lead to a return to the status quo. The report recommended close cooperation, clear deterrence policies, and Japan’s involvement.

United States Army-backed wargame blog, 2021.14 This United States Army-supported article provides a detailed narrative generated through a commercially available wargame. Ultimately, Taiwanese forces surrendered within a month. The People’s Liberation Army was able to utilize its modern, flexible forces near Taiwan, while their anti-access, area denial capabilities created problems that the United States forces were unable to overcome.

Studies post the start of Russia’s invasion of Ukraine:

Center for New American Security Dangerous Straits, June 2022.15 This study is set in 2026 and conducted a strategic-operational war game over Taiwan. Despite the People’s Liberation Army’s objective to decapitate Taiwanese leadership and inhibit a United States response with preemptive strikes on Japan and Guam, it indicated no quick victory for either side. Neither side had the upper hand after the first week. The wargame showed that a People’s Liberation Army presence in northern Taiwan possessed very vulnerable lines of communication. It also highlighted rapid escalation, crossed red lines, attacks on the Chinese and United States homelands, and a demonstrative nuclear detonation.

The study recommended the Department of Defense invest in long-range precision-guided weapons, undersea capabilities, additional basing in the western Pacific, and joint planning with Japan and Australia. It also noted the requirement to plan for a protracted conflict, mitigate escalation risks, and support Taiwan’s military posture.

Center for Strategic International Studies The First Battle of the Next War, 2022.16 This study is an impressively detailed and wide-ranging assessment of a war game involving China, Taiwan, Japan, and the United States. It examines conflict variations over twenty-four different iterations. It clearly details which factors increase or decrease Taiwan’s chances and is clear about assumptions and limitations. The study assessed that China was always able to get troops into Taiwan. People’s Liberation Army forces were so numerous and close that outright defeat at sea was impossible.

Conversely, the United States could not land any forces on Taiwan within the month the games were played. The studies found that the United States, Taiwanese, and Japanese forces prevailed if four key conditions held: Taiwan ground forces could hold out, Taiwan is properly supplied before a conflict, the United States could access bases in Japan, and the United States could rapidly strike the underway Chinese fleet. The study acknowledges that it is more optimistic regarding the chances for Taiwan and the United States, contrasting with some internal United States wargames (see above).

The study’s recommendations included clarifying war plans with Taiwan and Japan, expanding United States facilities near Taiwan, demonstrating a political willingness to incur heavy casualties, and preparing Taiwanese forces properly.

Insights and analysis

Trends over time. The reviewed wargame studies reveal a worsening trend for Taiwan and its defenders. The worrisome trend is especially pronounced for scenarios that take place in the period 2025-2030.17 Studies written before 2018 typically showed that the Republic of China and United States forces hold Taiwan at increasing cost. Studies after 2018 are more pessimistic, as the growing People’s Liberation Army capabilities and the inability of the United States to project sufficient power led to Taiwan’s defeat at worst or pyrrhic victories at best. However, this general trend is not uniform.18

The Russian invasion of Ukraine caused a reversal in this generally pessimistic trend. The latest studies reflect a greater uncertainty over the result of a Chinese invasion and the capabilities of its People’s Liberation Army. It became clearer that assessments need to model more factors, principally logistics, robust satellite-enabled communications, the introduction of greater numbers of uncrewed systems, and man-portable missiles. These factors all impeded Russia’s invasion. In recent studies, the changing character of warfare tended to favor a determined defender, which decreased China’s chances.

Whilst these newest studies are more optimistic for Taiwan, the identified general trend will worsen unless the United States enacts major improvements. Without massively increasing the number of missiles available and the ability to strike People’s Liberation Army transports, the Republic of China’s forces are overwhelmed. In most scenarios that assume the United States makes such changes, the coalition defeated a conventional amphibious invasion and maintained an autonomous and democratic Taiwan; however, no study resulted in the successful retaking of lost Taiwanese territory by allied forces. A successful defense of Taiwan would come at a high cost. Allied forces lose dozens of ships, hundreds of aircraft, and thousands of service personnel while Taiwan’s economy is devastated. Such high losses would damage the United States’ global position for many years.19

Explaining differences between the studies. It is worth considering how these wargaming studies come to such a range of different results. Wargaming is a valuable tool for commanders, leaders, and managers. Well-executed wargames before and during hostilities delivered significant competitive advantages in numerous conflicts, although wargaming does not, and cannot, guarantee success.20 The United States, China, and Taiwan have all wargamed the issue of Taiwan extensively.21 But wargaming studies tend not to be done if the answer is self-evident and beyond doubt. For example, no wargame assumes Taiwanese forces are unwilling to fight as China could then accomplish its objectives quickly and consolidate control.

Therefore, distinct scenarios are used in the various studies above to seek insights in different situations. Conflicts may include various actors and involve basing from a range of countries. Involved parties would use different concepts of operations, like a deliberate full-scale invasion or limited attack on outlying islands, with different levels of strategic and tactical warning for defenders and reinforcers. One alternative approach involved letting a Chinese invasion run out to see how long Taiwan could hold on while assuming some best-case scenario conditions for the People’s Liberation Army. The scenario provided insight into the allowable delay for the United States to intervene before the Taiwanese capitulation. The answer was thirty-one days after the initial People’s Liberation Army landings.22

This review does not cover how to conduct a wargame. Conducting wargames is covered in places like the Ministry of Defense wargaming handbook and the methodology sections of some wargame studies.23 However, setting assumptions is critical to validation and fidelity.24 Many factors need to be assumed, whether significant, like which parties are involved, or insignificant, like the chances a missile can knock a ship out of action. But even a relatively simple assumption could be initially in error or become outdated during a conflict as sides adapt their tactics. For example, the effectiveness of depth charges in the Second World War25 or the use of unmanned aerial vehicles in the sensor-kill chain in Ukraine were instances where initial assumptions did align with reality.26

Unless bound by a common rulebook, studies will make different assumptions. These can account for variations in results. The First Battle of the Next War, 2022, specifically looks at how its study differs from classified Department of Defense wargames.27 It asserts differences come from rival values attributed to the probability of kill, different aims and objectives of the wargames, the focus on shorter time frames (when United States forces are less ready), and assuming Chinese capabilities are more potent for a worst-case scenario hedging effort. Differences are exacerbated by changes in force structure, capabilities, and the relative power balance between the People’s Liberation Army and its adversaries in proximity.

Besides tactical probability of kill metrics, assumptions need to be made about other factors. Some will be easier to make than others. For example, the order of battle of all sides is unlikely to change significantly in the short term. Still, the organizers also need to assume which forces would be saved for other contingency operations. For example, forces reserved by the United States for Europe or for China to commit to the Indian border. Weapon stockpiles, the will to fight, the effectiveness of forces, the concept of operations, allied support, availability of future weapon systems, strategic messaging, and tactical warnings must all be decided and agreed upon by the adjudicators and players. Moreover, as wargames look further into the future, more unknown variables come into play, all of which will affect the play’s fidelity and outcome.

Each of these factors and variables could prove pivotal in a closely balanced conflict, to say nothing of the usual frictions. Furthermore, any general conflict involving the United States and China would likely include all domains of warfare at a scale not seen since the mid-20th century, cover a vast area of the western Pacific, and comprise actors using a range of new and some unknown and classified capabilities. Therefore, modeling a future United States versus China conflict is, perhaps, wargaming’s most difficult challenge.

Sensitivity analysis: What factors increase the chance the United States, Taiwan, and allies will prevail?

“All models are wrong, but some are useful.” – Attributed to statistician George Box28

While many studies differ, combining their findings can give valuable insights into what factors may prove pivotal in a future conflict. The most compelling conclusions arise from sensitivity analysis, which attempts to understand how different assumptions affect the outcome.29 These studies’ usefulness comes from testing the effects of different assumptions, as they demonstrate what factors would most increase or decrease the United States and Taiwan’s chances of victory.

The Center for Strategic International Studies’ The First Battle of the Next War, 2022, is the single best example of the comparative analysis of sensitive variables and is worth looking at closely. The study ran twenty-five different games, testing several variables the study deemed most important.30 The Center of Strategic International Studies identifies four critical conditions for success: Taiwan’s people and military must effectively resist, Taiwan must have sufficient stockpiles at the start of the war, the United States must begin operations against China immediately, and the United States must be able to use its bases in Japan for combat operations.31 Without these conditions, allied missiles and United States submarines were insufficient to defeat an invasion.

The report discusses the effects of twenty-five variables. The most important variables benefitting the People’s Liberation Army invasion were an isolated and indecisive Taiwan, a neutral Japan, delayed entry of United States combat forces (as much as D+14), and few modern anti-ship cruise missiles available to counter-invasion forces. The most important factors that benefit Taiwan’s defense were the People’s Liberation Army not being as proficient in conducting amphibious operations or defending their ships from missiles, immediate combat operations from the Japanese Self Defence Forces, increased hardened aircraft shelters in Japan, and more airbases or airports to conduct operations from for the United States.

From reading the studies in this review, the author considers these variables the most likely to determine the outcome of a conflict involving China, Taiwan, and the United States. First and foremost, the role of Japan (and, to a lesser degree, other allies) will be fundamental to Taiwan’s survival for two reasons. First, it increases and disperses the number of bases the United States can operate from, and second, it increases the mass and number of allied forces opposing China. The availability of Japanese and other regional bases, like the Philippines, increases the survivability and ability to surge assets into the theater of operations. A few Chinese strikes could utterly disrupt United States operations with just Guam and the United States’ nearby aircraft carriers. Adding Japanese and possibly other allied forces to the defensive order of battle makes it easier to increase fire rates against Chinese aircraft, ships, and transports.

People’s Liberation Army Navy vulnerability, or the ability to absorb attrition, is the vital kinetic variable. The more long-range missiles the coalition possesses and can direct against People’s Liberation Army invasion elements, the greater Taiwan’s chances. “They need anti-ship cruise missiles, sea mines, mobile artillery, mobile air defenses, unmanned aerial vehicles… It comes down to sinking about 300 Chinese ships in about 48 hours”.32 However, projected production rates of missiles like the Long-Range Anti-Ship Missile (LASRM) and maritime strike Joint Air-to-Surface Standoff Missile (JASSM) are limited, and in many wargames, the allies quickly deplete these specific missiles. The time needed to transport these missiles to relevant bases or ships affects wargame outcomes. If Taiwan has access to significant stockpiles of material at the start of the conflict, especially missiles, this buys Taiwan more time to await United States intervention. Additionally, with China’s anti-access capabilities limiting the effect of allied short-range air attacks, submarines offer an effective way to attack Chinese amphibious shipping. If United States submarines can reliably enter, engage in, escape, rearm, and return to Chinese shipping channels, Chinese chances for success are significantly diminished.

In most wargames without external support, the Republic of China’s forces remain effective only for a few weeks. Delays in the response of the Taiwanese, United States, Japanese, and allied forces significantly increased China’s chances. Delaying factors include allied indecision and the success of Chinese deception activities. While strategic surprise may be difficult to obtain, tactical surprise, like mounting an assault from fake exercises, increases China’s chances.

Fundamentally, the People’s Liberation Army and the People’s Liberation Army Navy’s success depends on two factors. First, China’s ability to project its anti-access capabilities further from its coast will make it increasingly difficult for the United States to deploy forces at sufficient ranges to affect the outcome of a conflict. The second factor is China’s ability to plan and execute an opposed amphibious assault. This is an important area of uncertainty identified in many studies where China’s inexperience could result in a disaster for them in numerous ways.33,34

Areas of most uncertainty that require further study

Wargaming on a Taiwan invasion inevitably has limitations. As noted earlier, the scope of this conflict could be vast. All operational domains and political, diplomatic, economic, and information effects are in play. Not all permutations of the assumptions nor the interdependent effects can be tested. For practical reasons, wargames tend to cover shorter periods than a conflict with the People’s Liberation Army might take. Furthermore, many developments in warfare were demonstrated in the Russia-Ukraine war, which wargames have only started to attempt to model.

Wargaming studies sometimes helpfully discuss what they do and do not model. For example, the RAND scorecard, which considers more aspects than most, does not consider ground combat or drones, and it does not model the effects of the threat of nuclear weapons.

At the strategic level, several variables have been marginalized or overlooked. Xi’s long rule and centralization of power follow the pattern of many other authoritarian leaders. A lack of robust internal challenge could lead to a greater chance of strategic misjudgments than wargames currently assume.35 One war game considered multiple crises simultaneously (Russia, China, and the Democratic People’s Republic of Korea).36 The West’s rivals would likely seek to take advantage of crises if they could, either during or after a conflict. The effects of nuclear weapons deterrence were replicated by players imposing limits on themselves, like restricting attacks against mainland Chinese assets,37 but this was rare. None of the other studies directly calculated the effect of the use of nuclear weapons, and their use was considered beyond the scope. Xi and the People’s Liberation Army likely took note of the effects of Russia’s nuclear threats against the North Atlantic Treaty Organization.

While some wargames model how long it takes various actors to engage in conflict, few have enough players to test Chinese efforts to break up coalitions and their impact on a conflict. The permutations of those alliances and coalitions are also worthy of study; the United States, Japan, and Taiwan are well covered but are not the only variations. With enough notice and favorable dispositions, other capable actors could become directly involved, like forward-deployed submarines from allies. China fears a multi-front war, so more consideration to Indian contingencies could be given. The role of other regional actors in South and South East Asia should be considered as active participants or potential threats that China needs to reserve forces to counter. Further, the will to fight for Taiwan’s population (and China’s effectiveness in undermining it) beyond its leadership has rarely been considered in depth.38 Still, it would be a vital contributor to the assessment. Most studies assume attacks would be limited or not occur in the United States and Chinese homelands. Some do,39 but more study is warranted on how such attacks could escalate or be deterred.

Similarly, the role of People’s Liberation Army forces based outside China is not covered. The People’s Liberation Army currently has limited self-defense capabilities, and China’s main effort will be concentrated on Taiwan. But, in later time periods, People’s Liberation Army bases worldwide could complicate allied intervention.40 As many studies find the most critical period is relatively short, studies on the effectiveness of sanctions and blockades are rare. Studies that look at economic sanctions tend not to consider military action and vice versa.41 Despite numerous predictions of long-duration conflict, most wargames consider a shorter, tightly bound period. Should China fail to take Taiwan, the Chinese Communist Party would be unwilling to give up its claim and accept the outcome. What China would do next is an important area for study.42 Barring state or party collapse, China would seek to rearm and re-contest the war. After and even during a period of conflict, the need to replenish stockpiles and material will be acute and could be wargamed.

Most studies assume China will deliberately mobilize military and civilian assets, like civilian sealift, that would be readily noticed unambiguously by the Taiwanese and other nations. China has a clear incentive to reduce the predictability of its efforts by staging more realistic-looking exercises to gain tactical, if not strategic, surprise. China’s normalization of increased activities, exercises, and incursions near Taiwan complicates allied decision-making.43 Furthermore, the invasion of Ukraine showed that not all allies perceived the warning signs and came to different conclusions regarding Russia’s intent.44 Some studies examined sensitivity analysis in the competing doctrines of the People’s Liberation Army and the Republic of China’s forces. However, the effects of the operational inexperience of the People’s Liberation Army and Taiwan should be better tested, especially on critical amphibious landings. Any conflict is unlikely to follow established and conditioned doctrine dogmatically. Besides mobilizing for a full-scale invasion, China could choose different coercive measures against Taiwan, including island seizures (salami slicing),45 maritime or air blockade, missile bombardment to destroy leadership or undermine will, or a surprise air assault.46 The United States’ concepts of operations will also change.47 Fighting in and around Ukraine has shown a significant increase in the use of drones for direct attacks and tactical reconnaissance. Wargames have not caught up with the increasing number and use of drones on battlefields, including at sea. While some studies note the growing role of larger drones in the air and maritime order of battles, more assessment of the role of drones in direct attacks and tactical reconnaissance, especially at long distances over the sea, will be needed. The robustness of drone data in electronic warfare must be examined. Reliable and resilient communication networks are required. China could quickly degrade Taiwanese command and control. However, China warily noted Ukraine’s ability to utilize massive proliferated low-earth orbit satellite constellations, like Starlink or OneWeb. Chinese losses would increase if Taiwan’s communications and computing networks were more robust.

United Kingdom (U.K.) military and civilian personnel from the Ministry of Defense (MoD) conducted a wargame on the High North as part of DSTL’s inaugural Influence Wargaming Conference on July 19th, 2021. With the Indo-Pacific and Australia, the United Kingdom, and the United States (AUKUS) of increasing importance to the U.K., the time is right for MoD to build on previous Taiwan/South China Sea wargames to develop its awareness and contingencies. Crown Copyright. Photographer: SAC Charlotte Hopkins, JIAG.

Conclusions

The wargaming and other studies reviewed here show a positive general trend over time for China. However, this is not a constant trend, and early findings from Russia’s invasion of Ukraine indicate China might encounter more problems than previously thought.

In most cases, wargaming studies still show that a China and Taiwan conflict, featuring a United States intervention, would be close run and incredibly bloody for all sides. There would also be severe effects on the global economy. If the People’s Liberation Army replicates these studies, they should have some deterrent effect on China.

The outcome of these studies is very sensitive to small changes, and the war in Ukraine demonstrated new developments and uncertainty. Further analysis is needed. However, those running wargames possess limited resources, so studies that last longer and cover the interactions of more types of capabilities in detail would be difficult to conduct.

Instead, a greater range of smaller studies, which each interrogate more of the areas of uncertainty identified above, is recommended. These should include wargames on what follows an initial failed Chinese invasion, different Chinese military options (especially blockades), and the use of drones and capabilities like Starlink or OneWeb. These studies could then inform assumptions used by the larger, more comprehensive wargames that happen periodically.

These smaller studies should include the potential benefits and risks of including more allies, like Australia and the United Kingdom. While the first weeks are crucial to the outcome, prior experience indicated that the United Kingdom will likely have capable maritime and other assets deployed in the western Pacific at the onset,48 and the planned Global Response Force49 will give the United Kingdom further options to reinforce regional allies within that pivotal timeframe.

Robert Kitchen is a First Sea Lord Fellow at the Royal Navy Strategic Studies Centre. He is also a U.K. Ministry of Defence Civil Servant with experience in U.K. Indo-Pacific policy and defense engagement. These views are his alone and do not represent those of the U.K. Ministry of Defence, Royal Navy Strategic Studies Center, or any other institution.

Endnotes

1. Jim Garamone, “Defense Official Says Indo-Pacific Is the Priority Theater; China Is DOD’s Pacing Challenge,” United States Department of Defense, March 9th, 2022. (Accessed August 23, 2023). https://www.defense.gov/News/News-Stories/Article/Article/2961183/defense-official-says-indo-pacific-is-the-priority-theater-china-is-dods-pacing/

2. For example, see: Tso-Juei Hei, “Taiwan Conducts Han Kuang 2022 Large-Scale Exercise,” Naval News, July 29th, 2022. (Accessed August 23rd, 2023). https://www.navalnews.com/naval-news/2022/07/taiwan-conducts-han-kuang-2022-large-scale-exercise/; & Joseph Yeh, “DEFENSE/Taiwan’s Han Kuang exercises to begin Monday with tabletop wargames,” Focus Taiwan, May 14th, 2023. (Accessed August 23rd, 2023). https://focustaiwan.tw/politics/202305140007 & Elsa B Kania & Ian Burns McCaslin. “Learning Warfare from the Laboratory – China’s Progression in Wargaming and Opposing Force Training,” Institute for the Study of War, September, 2021. (Accessed, August 23rd, 2022). https://www.understandingwar.org/report/learning-warfare-laboratory-china%E2%80%99s-progression-wargaming-and-opposing-force-training. For a quick and easy breakdown of Taiwan’s Han Kuang exercises from 2000 – 2020, see Wikipedia entry: https://en.wikipedia.org/wiki/Han_Kuang_Exercise#2020.

3. “Defence Wargaming Centre,” UK Ministry of Defence, April 23th, 2023. (Accessed August 23, 2023). https://www.gov.uk/guidance/defence-wargaming-centre; Press Release: “Announcement of new Director appointed to the Secretary of State’s Office for Net Assessment and Challenge (SONAC),” U.K. Ministry of Defence, May 6th, 2022. (Accessed August 23rd, 202). https://www.gov.uk/government/news/announcement-of-new-director-appointed-to-the-secretary-of-states-office-for-net-assessment-and-challenge-sonac

4. David C. Gompert, Astrid Stuth Cevallos, & Cristina L. Garafola. “War with China: Thinking Through the Unthinkable,” RAND Corporation, 2016. (Accessed August 23rd, 2023). https://www.rand.org/pubs/research_reports/RR1140.html

5. Eric Heginbotham, et al. “The United States-China Military Scorecard: Forces, Geography, and the Evolving Balance of Power, 1996–2017,” RAND Corporation, 2015. (Accessed August 23rd, 2023). https://www.rand.org/pubs/research_reports/RR392.html

6. Ian Easton. “The China Invasion Threat: Taiwan’s Defense and American Strategy in Asia,” Project 2049 Institute, 2017.

7. James Lacey. “How does the next Great Power conflict play out? Lessons from a wargame,” War on the Rocks, April 22nd, 2019. (Accessed August 23rd, 2023).https://warontherocks.com/2019/04/how-does-the-next-great-power-conflict-play-out-lessons-from-a-wargame/.

8. Kyle Mizokami. “The United States Military ‘Failed Miserably’ in a Fake Battle Over Taiwan,” Popular Mechanics, August 2nd, 2021. (Accessed August 23rd, 2023). https://www.popularmechanics.com/military/a37158827/us-military-failed-miserably-in-taiwan-invasion-wargame/.

9. David Vergun. “DOD Focuses on Aspirational Challenges in Future Warfighting,” United States Department of Defense, July 26th, 2021. (Accessed August 23rd, 2023). https://www.defense.gov/News/News-Stories/Article/Article/2707633/dod-focuses-on-aspirational-challenges-in-future-warfighting/; & Brett Tingley. “Joint Chiefs Seek A New Warfighting Paradigm After Devastating Losses In Classified Wargames,” The Drive, July 27th, 2021. (Accessed August 23rd, 2023). https://www.thedrive.com/the-war-zone/41712/joint-chiefs-seek-a-new-warfighting-paradigm-after-devastating-losses-in-classified-wargames.

10. “Defending Taiwan is growing costlier and deadlier,” The Economist, October 8th, 2020. (Accessed August 23rd, 2023. https://www.economist.com/asia/2020/10/08/defending-taiwan-is-growing-costlier-and-deadlier; & Richard Bernstein. “The Scary War Game Over Taiwan That the United States Loses Again and Again,” RealClear Investigations (August 17, 2020). Accessed August 23, 2023:

https://www.realclearinvestigations.com/articles/2020/08/17/the_scary_war_game_over_taiwan_that_the_us_loses_again_and_again_124836.html.

11. Valerie Insinna. “A United States Air Force war game shows what the service needs to hold off — or win against — China in 2030,” DefenseNews, April 12th, 2021. (Accessed August 23rd, 2023). https://www.defensenews.com/training-sim/2021/04/12/a-us-air-force-war-game-shows-what-the-service-needs-to-hold-off-or-win-against-china-in-2030/.

12. Chris Dougherty, Susanna V. Blume, Becca Wasser, and Dr. ED McGrady. “Slaughter in the East China Sea’, Center for a New American Security, August 7th, 2020. (Accessed August 23rd, 2023). https://www.cnas.org/press/in-the-news/slaughter-in-the-east-china-sea. Original publication: Michael Peck. “Slauther in the East China Sea,” Foreign Policy,August 7th, 2020. (Accessed August 23rd, 2023). https://foreignpolicy.com/2020/08/07/slaughter-in-the-east-china-sea/.

13. Chris Dougherty, Jennie Matuschak and Ripley Hunter. “The Poison Frog Strategy,” Center for a New American Security, October 26th, 2021. (Accessed August 23rd, 2023). https://www.cnas.org/publications/reports/the-poison-frog-strategy.

14. Ian Sullivan. “337: ‘No Option is Excluded’ — Using Wargaming to Envision a Chinese Assault on Taiwan,” Mad Scientist Laboratory, July 1st, 2021. (Accessed August 23rd, 2023). https://madsciblog.tradoc.army.mil/337-no-option-is-excluded-using-wargaming-to-envision-a-chinese-assault-on-taiwan/

15. Stacie Pettyjohn, Becca Wasser and Chris Dougherty. “Dangerous Straits: Wargaming a Future Conflict over Taiwan,” Center for a New American Security, June 15th, 2022. (Accessed August 23rd, 2023). https://www.cnas.org/publications/reports/dangerous-straits-wargaming-a-future-conflict-over-taiwans

16. Mark F. Cancian, Matthew Cancian, & Eric Heginbotham.”‘The First Battle of the Next War: Wargaming a Chinese Invasion of Taiwan,” Center for Strategic and International Studies, January 9th, 2023. (Accessed August 23rd, 2023). https://www.csis.org/analysis/first-battle-next-war-wargaming-chinese-invasion-taiwan

17. See “Defending Taiwan is growing costlier and deadlier,” The Economist, October 8th, 2020; & Richard Bernstein, Op Cit.

18. Valerie Insinna, Op Cit.

19. Mercy A. Kuo & Mark Cancian. ”Wargaming a Chinese Invasion of Taiwan: ‘Victory Is Not Enough,”, The Diplomat, January 31st, 2023. (Accessed August 23rd, 2023). https://thediplomat.com/2023/01/wargaming-a-chinese-invasion-of-taiwan-victory-is-not-enough/

20. Developments Concepts and Doctrine Centre (DCDC). MOD Wargaming Handbook, UK Ministry of Defence, August, 2017. (Accessed August 23rd, 2023). https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/641040/doctrine_uk_wargaming_handbook.pdf. For a view of the effectiveness of wargames during war, see Simon Parkin. “A Game of Birds and Wolves: The Secret Game that Won the War,” Sceptre: London, 2019. Parkin explores the work of the Western Approaches Tactical Unit; a small team of Royal Navy Reserve and Women’s Royal Navy Service personnel credited with devising the tactics, techniques, and procedures for anti-submarine operations during the Battle of the Atlantic.

21. Elsa B. Kania & Ian Burns McCaslin, Op Cit.

22. Max Stewart. “Island Blitz: A campaign analysis of a Taiwan takeover by the People’s Liberation Army,” Center for International Maritime Security, June 13th, 2023. https://cimsec.org/island-blitz-a-campaign-analysis-of-a-taiwan-takeover-by-the-pla/

23. See Chapter 2, MoD Wargaming Handbook, Op Cit.; & Mark F. Cancian, Matthew Cancian, & Eric Heginbotham, Op Cit.

24. Elizabeth Bartels. ”Getting the Most out of your Wargame: Practical Advice for Decision Makers,” War on the Rocks, November 19th, 2019. (Accessed August 23rd, 2023). https://warontherocks.com/2019/11/getting-the-most-out-of-your-wargame-practical-advice-for-decision-makers/.

25. Raymond H. Milkman. “Operations Research in World War II,” Proceedings, Vol 94/5/783, United States Naval Institute, May 1968. (Accessed August 23rd, 2023). https://www.usni.org/magazines/proceedings/1968/may/operations-research-world-war-ii.

26. David Hambling. “How Drones Are Making Ukrainian Artillery Lethally Accurate,” Forbes, May 12th, 2022. (Accessed August 23rd, 2023). https://www.forbes.com/sites/davidhambling/2022/05/12/drones-give-ukrainian-artillery-lethal-accuracy/

27. Mark F. Cancian, Matthew Cancian, & Eric Heginbotham. Op Cit. p102.

28. George E. P. Box. “Science and Statistics,” Journal of the American Statistical Association, 71 (356), 1976: 791-799. DOI:https://doi.org/10.1080%2F01621459.1976.10480949.

29. Mark F. Cancian, Matthew Cancian, & Eric Heginbotham. Op Cit: 36.

30. See Annex A, Mark F. Cancian, Matthew Cancian, and Eric Heginbotham. Op Cit.

31. Mercy A. Kuo & Mark Cancian. Op Cit.

32. Richard Bernstein. Op Cit.

33. Eric Heginbotham, et al. Op Cit: 21.

34. Chapters 4 and 5 in Ian Easton. Op Cit.

35. Hal Brands. “Putin Has Fallen Victim to the Dictator’s Disease,” American Enterprise Institute, April 7th, 2022. (Accessed August 23rd, 2023). https://www.aei.org/op-eds/putin-has-fallen-victim-to-the-dictators-disease/.

36. James Lacey. Op Cit.

37. Stacie Pettyjohn, Becca Wasser & Chris Dougherty. Op Cit.

38. The Economist. Op Cit.

39. Stacie Pettyjohn, Becca Wasser and Chris Dougherty. Op Cit.

40. Cristina L. Garafola, Stephen Watts, Kristin J. Leuschner. “China’s Global Basing Ambitions: Defense Implications for United States,’ RAND Corporation, 2022. (Accessed August 23rd, 2023). https://www.rand.org/pubs/research_reports/RRA1496-1.html.

41. Charlie Vest and Agatha Kratz. “Sanctioning China in a Taiwan crisis: Scenarios and risks,” Atlantic Council, June 21st, 2023. (Accessed August 23rd, 2023). https://www.atlanticcouncil.org/in-depth-research-reports/report/sanctioning-china-in-a-taiwan-crisis-scenarios-and-risks/.

42. E.g. see Executive Summary in Stacie Pettyjohn, Becca Wasser & Chris Dougherty. Op Cit.

43. Bonny Lin & Joel Wuthnow. “Pushing Back Against China’s New Normal in the Taiwan Strait,” War On The Rocks, August 16th, 2022. (Accessed August 23rd, 2023).https://warontherocks.com/2022/08/pushing-back-against-chinas-new-normal-in-the-taiwan-strait/

44. Patrick Wintour. “Why are Germany and France at odds with the Anglosphere over how to handle Russia?” The Guardian, January 26th, 2022. (Accessed August 23rd, 2023). https://www.theguardian.com/world/2022/jan/26/nato-allies-policy-russia-ukraine-analysis

45. Chris Dougherty, Jennie Matuschak & Ripley Hunter. Op Cit.

46. The Economist. Op Cit; & David Lague & Maryanne Murray. “T-Day:The Battle for Taiwan,” Reuters Investigates, November 5th, 2021. (Accessed August 23rd, 2023). https://www.reuters.com/investigates/special-report/taiwan-china-wargames/

47. Valerie Insinna. Op Cit.

48. Prime Minister’s Office. “Fact sheet: Trilateral Australia-UK-United States Partnership on Nuclear-Powered Submarines,” U.K. Government, March 13th, 2023. (Accessed August 23rd, 2023). https://www.gov.uk/government/publications/joint-leaders-statement-on-aukus-13-march-2023/fact-sheet-trilateral-australia-uk-us-partnership-on-nuclear-powered-submarines; & Press Release: “H.M.S. Daring deployment to boost UK response to Philippines typhoon,” U.K. Ministry of Defense, November 12th, 2013. (Accessed August 23rd, 2023). https://www.gov.uk/government/news/hms-daring-deployment-to-boost-uk-response-to-philippines-typhoon

49. U.K. Ministry of Defense. “Defence’s response to a more contested and volatile world,” HH Associates, 2023. (Accessed August 23rd, 2023). https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1171269/Defence_Command_Paper_2023_Defence_s_response_to_a_more_contested_and_volatile_world.pdf

Featured Image: Fighter jets attached to a brigade of the PLA Air Force Xi’an Flying College taxi on the runway in an Elephant Walk formation before taking off for a flight training exercise in early February 2024. (eng.chinamil.com.cn/Photo by Cui Baoliang)