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Undersea

Neither Fish nor Fowl: China’s Development of a Nuclear Battery AIP Submarine

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By Dr. Sarah Kirchberger and CAPT Christopher P. Carlson, USN (Ret)

On September 27, 2024, news broke that a previously unreported new type of Chinese nuclear-powered submarine, dubbed the “Type 041,” had suffered a major mishap at its fitting out pier at the Wuchang shipyard in Wuhan, according to unnamed Pentagon sources. Submarine expert Thomas Shugart had previously spotted an unknown submarine with a distinct x-shaped stern at Wuchang Shipyard from satellite imagery taken on 26 April 2024, and days later reported unusual crane activity at the same pier location from June 2024 imagery, speculating that the new boat suffered a serious incident.

Even more intriguing and consequential than the question of whether a submarine incident of some sort actually did occur at Wuchang or not, is however another issue: What type of “nuclear-powered submarine” could this new design possibly be?

China watchers were quick to point out that the Wuchang Shipyard in Wuhan had not hitherto built any nuclear submarines, although the shipyard’s facilities were completely rebuilt at a new location (from 2012-2020) and massively enlarged. All Chinese nuclear-powered attack submarines (SSN) and ballistic missile submarines (SSBN) have so far been constructed exclusively at the Bohai Shipyard at Huludao. The imagery of the new submarine makes it clear it is too small for a SSN, and is similar in size to China’s Type 039A/B/C Yuan series of conventionally powered submarines. Another interesting indicator was the reported type number – “041” – which is a continuation of the traditional numbering scheme carried by China’s diesel-electric submarines. By contrast, China’s nuclear-powered subs, whether SSNs or SSBNs, all have official type numbers starting with “09.” The next-generation Type 095 SSN and Type 096 SSBN are possibly already under construction at the Bohai Shipyard in Huludao, and there is no plausible suggestion that the smaller, unknown boat observed in Wuhan could represent either of those two platforms, given the larger estimated displacement of the Type 095 and Type 096 compared with the previous generation of Chinese SSNs and SSBNs.

A new type of nuclear battery AIP propulsion?

It would have been easy to dismiss the news of a supposedly nuclear-powered Type 041 submarine built in Wuhan as misinformation, were it not for the fact that several years earlier Chinese sources had hinted at a project for developing small, low power auxiliary nuclear reactors for conventional submarines, replacing the Stirling engine air-independent power system (AIP) that China developed based on a technology transfer from Sweden during the 1980s. A 2017 report by Richard D. Fisher described some details of such a plan based on slides from an academic lecture given by retired Rear Admiral Zhao Dengping.

Despite successfully developing a Stirling engine-based AIP system, China is known to have struggled with developing a more advanced, fuel cell-based AIP system as is currently in use with the German, South Korean and Singaporean navies, among others. Neither has China deployed lithium-ion batteries aboard its submarines, as pioneered by Japan. Here, Chinese analyses have stressed unresolved issues regarding the danger of thermal runaway, which poses heightened risks of a severe fire aboard a submerged submarine.

In light of such technical challenges, China may have decided to forgo developing high power density fuel cells or even more powerful Stirling engines for submarine applications, even though lithium-ion batteries are probably still on the table, opting for a different solution altogether by developing a nuclear battery.

Interestingly, as reported by R.D. Fisher, Rear Admiral Zhao Dengping’s lecture slides described just such a nuclear battery project. Of the presentation slides posted online, three dealt specifically with a small-scale nuclear reactor for conventional submarine platforms. One slide showed a basic schematic diagram that depicted a possible layout of the nuclear-powered electric propulsion plant. The reactor itself is described as a low pressure, low temperature design that employs natural circulation in the primary loop. Steam is generated, however, through an intermediate loop that appears to be in a separate compartment, which is then sent to a secondary loop with a conventional steam driven turbine generator in yet another compartment. While this design suggests an emphasis on safety, it does so at the expense of internal volume requirements and thermodynamic efficiency.

It is reasonable to ask if these slides accurately reflect Chinese intentions. With the benefit of hindsight, the response would be a confident “yes” because every slide posted from RADM Zhao’s lecture showed a platform or system that was then in service, undergoing testing, or was in the advanced research and development stage. For example, Zhao presented a slide that discussed a large deck amphibious assault ship – larger than the Type 075. The computer-generated graphic on the slide is very similar to the Type 076 currently under construction at the new Hudong-Zhonghua shipyard on Changxing Island. Another slide depicted an anti-ship ballistic missile (ASBM) engagement launched from a surface ship. This too has come to fruition when a video of a Type 055 launching an ASBM was posted in April 2022. These two examples of a platform or system that hadn’t been known to exist in 2017, but became evident years later, demand that the small reactor concept be taken seriously.

Some seven years after RADM Zhao’s slides became public, on 24 April 2024, a Chinese news article claimed that, in honor of the 75th birthday of the PLA Navy, a “new nuclear-powered submarine installed with a domestically produced small nuclear reactor” and based on the hull design of the conventionally powered “Type 039C” AIP sub was in development at the Wuchang shipyard in Wuhan. Note, this article came out a mere two days before the satellite images of the shipyard were taken and subsequently analyzed by Tom Shugart. The article compares the new Type 041 submarine design to an enlarged French Rubis class and states that its submerged displacement would be around 4,000 tons and thus larger than the Rubis, allowing it to integrate more capable sensor and weapon systems. The article describes the small auxiliary reactor as a “low-temperature, low-pressure, subcritical nuclear reactor” to “directly charge” the boat’s battery rather than drive the propeller. This describes a nuclear battery AIP system that allows the battery to be charged continuously while the boat is submerged and would eliminate the need to surface every 20 days as in the case of China’s Stirling AIP submarines.

The article goes on to say the first one or two units of the Type 041 would likely be used as prototypes for weeding out technical issues before any further units would be produced. It speculates that if the development is successful, even older conventional submarines could be gradually retrofitted with a nuclear battery AIP system. The article states that this could potentially transform China’s conventional submarine fleet into a fully nuclear-powered fleet. Despite some questionable technical conclusions by the author, the article is consistent with Zhao’s lecture material.

What is a nuclear battery?

The reference to a “small” reactor on the Type 041 should be understood in the context of existing submarine reactors, which produce between 70 – 190 megawatts of thermal power (MWt) depending on the design and all belong to the category of microreactors. These reactors are defined by the International Atomic Energy Agency as having a power generation capability of less than 50 megawatts of electrical power (MWe), or approximately 220 MWt. Most microreactors are in the 1 – 20 MWe (≈6 – 125 MWt) range; the nuclear battery resides at the bottom end of this category. Nuclear batteries are loosely defined as nuclear reactors that produce up to 20 MWt or approximately 3 MWe. These reactors are indeed “small” in comparison to those on larger SSNs and SSBNs and can fit into a Type 039A/B/C submarine pressure hull that is about 7.1 meters in diameter.

While rather scarce, nuclear batteries have been used in submarine and submersible designs before: the American NR-1 (≈1 MWt), the Soviet Project 651E Juliett with the VAU-6 (4.9 MWt) boiling water reactor, the Project 20120 Sarov, and the collection of deep-diving submersibles of the Soviet/Russian Main Directorate of Deep-Sea Research or GUGI, including Project 1851 X-Ray, Project 1851.1 Paltus, Project 1910 Uniform, and Project 1083.1 Losharik, reported to have a pressurized water reactor in the 10 – 15 MWt range. Lastly, Canada conducted considerable research in the late 1980s to develop a “baby nuke” submarine using an Autonomous Marine Power Source or AMPS-1000 powerplant with a maximum design power of 10.8 MWt.

Based on RADM Zhao’s description that the small reactor being considered operates at low pressure and low temperature, it is reasonable to assume a maximum thermal power rating of 10 – 11 MW – consistent with Soviet and Canadian experience. The thermodynamic efficiency would be on the low side for historical nuclear batteries, around 12% – 13%, due to the losses involved with the additional intermediate steam generation loop as shown in the system diagram slide. Despite the low efficiency, such a nuclear power plant could generate about 1.3 MWe, four to five times that of any conventional AIP system. The hull size of the Type 041 revealed in satellite imagery is sufficiently large to accommodate the design as shown, but even with the additional 7 meters in length, the Stirling engines and cryogenic oxygen storage would have to be removed to free up additional volume.

Operational advantages of a nuclear battery

All types of advanced conventional AIP propulsion systems, whether fuel cell, Stirling engine, or steam turbine based, offer extended submerged endurance to small and medium size submarines when compared with traditional diesel-electric propulsion systems, such as that fitted to the Project 636M Kilo-class China imported from Russia. The latter typically needs to come up to snorkeling depth every day for two to three hours to recharge its batteries, assuming a 10% – 12% indiscretion rate, thus greatly increasing the risk of detection. At best, a Kilo-class submarine can stay submerged at slow speed for about three days before needing to snorkel. Chinese analysts have in the past lamented the fact that this limitation exposes Chinese submarines to adversary anti-submarine warfare (ASW) forces just when they are about to reach deeper diving depths in the Okinawa Trough after leaving port in East China. Any AIP system would help to alleviate this predicament, but the maximum submerged transit speed of a submarine utilizing a conventional AIP system is still only 4 – 6 knots. A nuclear battery AIP system as described above could support submerged transit speeds of up to 9 – 10 knots while meeting all hotel loads and the electrical power requirements of the nuclear plant auxiliaries.

Another advantage that is often not discussed is that there is ample electrical power available to outfit a Type 041 with a full spectrum of atmospheric control equipment. Conventional AIP boats still need to ventilate daily to renew the atmosphere with fresh air, unless the crew relies on a limited supply of consumable chemical systems to purge carbon dioxide and carbon monoxide from the atmosphere. Oxygen isn’t a problem as the crew can vent off a little from the AIP cryogenic oxygen tank to support their needs. A Type 041 can feasibly be fitted with compact oxygen generators, carbon dioxide scrubbers, and carbon monoxide-hydrogen burners, thereby giving the submarine complete independence from outside air.

Lastly, despite what the advertising brochures say, conventional AIP systems do not charge submarine storage batteries well. They can keep a fully charged battery topped off, but recharging a battery that has been significantly discharged is really not a viable option. Russian brochure data on the Project 636 Kilo states that it would take about 12 hours to recharge a completely discharged battery; this is with most of the output of two 1.5 MW DC generators run by the diesel engines. A conventional AIP system would be hard pressed to produce even a tenth of the power that diesel-driven DC generators can provide – this means multiple days to fully recharge a very low battery. A nuclear battery AIP system would be more capable of recharging a battery, but it will still take longer than using the diesel-driven DC generators. The main advantage in this case is the nuclear AIP system could support sufficient speeds to move the submarine clear of a possible ASW threat so that the diesel generators could be used to recharge the battery.

This severe limitation is why most AIP submarine crews tend to operate their boat like a traditional diesel-electric submarine for as long as they can, holding the AIP system in reserve for those tactical situations that demand greater stealth. By contrast, a nuclear battery AIP system turns this operating concept on its head. The crew can rely on the reactor to meet all their operating needs, allowing them to hold the battery in reserve to deal with those rare occasions where higher speed sprints are required to approach a target. In other words, a “SSn,” if you will, can patrol like a larger nuclear attack submarine, but because it lacks high-speed endurance would have to resort to conventional submarine approach tactics as the situation demands.

Due to their smaller size and comparative quietness, a SSn is better suited than larger SSNs to area-denial missions in shallow, coastal waters where the environment would make it difficult to detect a nuclear battery AIP platform; this makes them likewise useful for intelligence and mining missions. Whenever greater speed and longer steaming distances are required, however – for instance when hunting an adversary carrier strike group or tracking and trailing SSBNs on the high seas – their limitations render the SSn unsuitable. China, in light of its complex maritime geography of shallow littorals, does have an enduring requirement to operate both smaller coastal submarines for area denial missions in the Near Seas, as well as larger SSNs and SSBNs for its nuclear deterrence and missions in the Far Seas.

Could China have developed a nuclear battery AIP alone?

China has had difficulties in designing modern, reliable, and safe nuclear reactors for its next generation SSNs and SSBNs and reportedly has turned to Russian assistance in the recent past. This raises the question whether Russian help was also involved in developing China’s nuclear battery AIP submarine propulsion. Although open-source information falls short of a definitive answer, some indications hint at Russian assistance.

Firstly, the Soviet Union, and later Russia, have the most operational experience with this type of propulsion plant. The Soviet and Russian navies have operated nine relevant submarines, including the Project 651E Juliett and the Project 20120 Sarov, with the majority assigned to GUGI. Given that most of these nuclear battery plants were designed and built in the 1980s, Russia’s defense establishment would likely feel comfortable in sharing detailed design information on the older systems as well as providing technical support to China’s endeavors.

Secondly, Russia has previously transferred other types of nuclear propulsion technology to China. CMSI reported in 2023 that an agreement concluded in 2010 between Rosatom and the China Atomic Energy Agency for the expansion of Russian-Chinese joint nuclear power programs – including floating nuclear power plants – gave China “access to detailed technical information on the nuclear reactors Russia was installing on their nuclear power barges and new icebreakers.” These reactors either didn’t fully address China’s military needs or were too large for installation aboard a submarine, but nonetheless this transfer indicates a general willingness of Russia to provide China sensitive nuclear reactor technology.

Thirdly, there have been announcements that China and Russia are collaborating on a novel type of small submarine design. Already in 2015, reports indicated a Chinese interest in procuring four Lada-class submarines from Russia – a purchase that was never followed through in light of the Lada-class’s vexing technical issues. However, on August 25, 2020, quoting an official representative of the Federal Service for Military-Technical Cooperation (FSMTC), Russian state media announced that Russia and China were “jointly designing a new generation non-nuclear submarine.”

Although no further public information about this new type of jointly developed conventional submarine has since been disclosed, in October 2020, Vladimir Putin gave an intriguing answer to a question on Russian-Chinese relations at the 17th Valdai Annual Meeting:

“We have achieved a high level of cooperation in the defence industry—I am not only talking about the exchange or the purchase and sale of military products, but the sharing of technologies, which is perhaps most important. There are also very sensitive issues here. I will not speak publicly about them now, but our Chinese friends are aware of them. Undoubtedly, cooperation between Russia and China is boosting the defence potential of the Chinese People’s Army, which is in the interests of Russia as well as China.”

Though the nature of these “very sensitive” technologies remains unclear, submarine technology certainly fits the description, and in September 2024, news reports indeed indicated that Russia was supporting China with improving the nuclear propulsion plant of its next-generation Type 096 SSBN.

Fourth and lastly, Russia and China have for several years steadily enhanced their collaboration in sensitive anti-submarine warfare related technology areas – including fiber-optic hydrophones and underwater communication. This could be related to a general trend in their subsurface warfare cooperation.

Could the jointly developed Russian-Chinese “new generation non-nuclear submarine” be the Type 041? The apparent contradiction between the Russian statements and the arguments presented in this article could be accounted for if neither the Chinese nor the Russians consider this a traditional nuclear submarine, but a conventional submarine that uses a nuclear battery AIP system. Semantics? Perhaps, but this premise would also provide a rationale as to why the Type 041 was constructed at Wuchang instead of Huludao.

At this stage, it is not possible to determine whether the reported nuclear-powered Type 041 submarine spotted at Wuchang is related to the joint submarine collaboration that was announced in 2020. This new submarine could be solely a Chinese project, or a Chinese project that received some technical aid from Russia. None of these possibilities can be excluded.

The mutual benefits of collaboration on sensitive submarine technology

Russia, despite its superiority in the field of building nuclear submarines, has long struggled to develop AIP propulsion for its smaller conventional submarines. Russian industry representatives have envied China’s successful Stirling engine-based AIP system, going so far as to admit that the Rubin Design Bureau, when trying to develop fuel cell AIP and lithium-ion battery technology at the same time, was spreading itself too thinly and therefore did not succeed.

China, for its part, has lagged behind Russia in nuclear propulsion technology and has in the past received help from Russia in that area. The known transfers of Russian nuclear reactor technology might therefore just be the tip of the iceberg. There are thus clearly potential synergies that could be exploited. Joining forces to improve Chinese AIP with a small auxiliary nuclear reactor might be a project in which both sides could bring their respective strengths to the table while each profiting from a common submarine design. This hypothesis needs to be evaluated in the light of future information as it becomes available.

Since at least 2023, there has been speculation about the possibility that Russia might opt to rejuvenate its war-depleted fleet by ordering naval vessels from Chinese shipyards, which can offer competitive prices and superior production capacity, even for highly complex warships, when compared with cash-strapped Russian yards. On July 5, 2023, a Chinese news article reported a visit by Russia’s Navy Commander-in-Chief Yevmenov to the Jiangnan shipyard in Shanghai. The article frankly discussed the possibility that Russia might opt for Chinese shipyard orders to solve its production capacity problems – noting however that this would be possible only “if Russia can overcome its pride.” A joint submarine design could, however, be produced in parallel by Chinese and Russian shipyards.

Opting for an advanced, nuclear battery AIP design would also make operational sense for Russia, not least because the whole concept originated from the Soviet Union in the 1970s.

Russia is at a disadvantage vis-à-vis NATO submarines in the shallow and confined undersea domain of the Baltic Sea, where its traditional nuclear-powered submarines can’t operate as efficiently as in deeper water. For that theater alone, a more capable, smaller AIP submarine would be desirable – and likewise for the Black Sea, Barents Sea, and parts of the Arctic Ocean, where Russia also routinely encounters NATO navies. In particular the recent Norwegian-German Type 212CD class submarine cooperation would be a serious concern for Russia on its northern flank. The pressure of having to meet those challenges, against the backdrop of Russia’s increasingly lopsided dependency on Chinese political and economic support due its war against Ukraine and Russia’s reduced shipbuilding production capacity, may have induced Russia to agree to a joint development of nuclear battery AIP submarines.

Even without an official agreement, there is the possibility that Russia’s arms industries could be faced with a brain drain of Russian specialists towards China, as Russia’s economic crisis worsens. There could thus be informal, behind-the-scenes Russian involvement even in a “purely indigenous” Chinese submarine program.

Conclusion

So far, the limited information on a new Type 041 submarine spotted on satellite imagery at Wuchang Shipyard yields more questions than answers. The above musings should be treated as hypotheses, to be revised as new data emerges. However, given the rapid modernization of China’s military, and particularly its navy, it seems advisable to keep an eye on the likelihood that the Type 041 submarine could be sporting a novel, auxiliary nuclear powerplant in place of the Stirling engine previously employed in its AIP propulsion system. Furthermore, such an improvement may have been derived from Soviet (and now Russian) technology, which pioneered auxiliary nuclear batteries for submarines during the 1980s. And if that were the case, the Type 041 may be the outcome of a Russian-Chinese collaboration on a new type of conventional submarine as announced by Russian state media in 2020.

Lastly, even if the Type 041 is indeed a novel kind of nuclear-powered small submarine, the Chinese SSN and SSBN programs (Type 095 and 096) will almost certainly continue because they are independent submarine development projects that are designed for distinctly different operational roles. Indeed, suggestions that the reported flooding casualty suffered by the Type 041 constitutes a major setback in China’s nuclear submarine program is overstated. The development of a smaller nuclear AIP submarine is completely segregated from the Type 095 and 096 production effort – an effort the Huludao Shipyard was enhanced to meet. At worst, the Type 041 mishap is a minor speedbump in China’s overall submarine modernization plans.

If the theories on the nuclear battery propulsion system presented above are confirmed, then the Type 041 SSn is neither fish, nor fowl. It would possess some, but not all, of the benefits associated with a traditional nuclear-powered attack submarine. In short, it would be a tertium quid – a third something – designed to specifically address China’s geographical and geopolitical concerns in the Near Seas.

Dr Sarah Kirchberger is Director of the Institute for Security Policy at Kiel University (ISPK) and Vice President of the German Maritime Institute (DMI). She is the author of Assessing China’s Naval Power and editor of Russia-China Relations: Emerging Alliance or Eternal Rivals?. Formerly an Assistant Professor of Sinology at the University of Hamburg, she has also served as a naval analyst with shipbuilder TKMS. She holds a M.A. and a PhD in Sinology from the University of Hamburg. 

Christopher Carlson is a retired U.S. Navy Reserve captain and Department of Defense naval systems engineer. He began his navy career as a submariner and transitioned to the scientific and technical intelligence field in both his reserve capacity and in his civilian job. He is one of the co-designers, with Larry Bond, of the Admiralty Trilogy series of tactical naval wargames – Harpoon V, Command at Sea, Fear God & Dread Nought, and Dawn of the Battleship. He has also authored numerous articles in the Admiralty Trilogy’s bi-annual journal, The Naval SITREP, on naval technology and combat modeling.

Featured Image: A PLA Navy submarine steams during a training exercise in the Yellow Sea. (PLA photo)

Theory

Can John Arquilla’s Rules of New Age Warfare Be Taken to Sea?

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By Robert C. Rubel

Thomas Friedman’s 13 April New York Times opinion piece recounts an interview with John Arquilla, a distinguished former grand strategy instructor at the Naval Postgraduate School.  In explaining Ukraine’s impressive military performance in the face of the Russian invasion, Arquilla cites three rules of new age warfare from his book Bitskrieg: The New Challenge of Cyberwarfare, and their application is quite fitting.  If these rules concocted for cyberwarfare apply to ground warfare, might they also apply to warfare at sea?  If so, what are the implications?

Arquilla’s three rules are as follows:

  1. Many and small beats large and heavy
  2. Finding always beats flanking
  3. Swarming always beats surging

These rules are few and simply stated – generally a good thing when it comes to parsing a complex phenomenon like war.  And they do have a true new age feel to them; terms like many, small, finding, and swarming convey the notion that information technology in the form of micro-miniaturization makes even small weapons more powerful.  That said, there are words in the rules that raise alarms; categorical words like always convey a superficiality that experienced warfighters and analysts immediately suspect. But nonetheless, it is worth exploring how these rules could impact future naval warfare and fleet design.

Rule 1: Many and Small Beats Large and Heavy

As missiles become faster, longer range, smarter, and even harder to defeat, they might very well challenge the traditional relationship between capability and tonnage. The introduction of potent hypersonic missiles adds saliency to the application of this rule to naval warfare, calling into question the vulnerability of large capital ships such as nuclear-powered aircraft carriers. The most powerful weapons of yore, namely major caliber guns and jet aircraft, required large hulls to support their operations and the remainder of fleet design followed from there. However, missiles tend to break the relationship between weapon power and ship displacement, just as they break the relationship between capability and cost; hundreds of thousands of Tomahawk missiles could have been bought for the same price as the F-35 program. 

A missile-centric fleet design that took advantage of the new opportunities might consist of numerous smaller units of various types. The nascent U.S. Marine Corps concept of small detachments operating anti-ship missile launchers from dispersed locations reflects that logic as does – albeit incompletely – the U.S. Navy’s concept of Distributed Maritime Operations. Operating a highly dispersed force would complicate enemy targeting.

Moving past the categorical nature of the rule, we must also acknowledge that operating dispersed forces in the maritime environment is not the same as small groups of soldiers toting Javelin anti-tank missiles. For starters, deploying and sustaining a dispersed force will be more difficult than current battle groups composed of large ships. Then there is the matter of command and control. Since the conceptual emergence of “network-centric warfare” in the late 1990s, the vision of a dispersed, heterogeneous force knitted together by a network has been at least the tacit basis for communications and data processing developments. The various challenges to realizing this vision have not yet been overcome, and so adopting highly dispersed operations before such a comprehensive and resilient battle force network is operational would require a new and more sophisticated approach to mission command. These are just a few concerns that make application of the rule at sea less than straightforward. Nonetheless, the inherent character of modern missiles does add credibility to the rule when it comes to naval warfare.

Rule 2: Finding Always Beats Flanking

Putting aside the word always, the rule would not at first glance seem to apply at sea, where ships can maneuver “fluidly” as it were. There is perhaps some whiff of flanking in the concept of threat sector. If battle group defenses, say the positioning of escorts or combat air patrol stations is oriented on an expected threat sector, then an enemy that can succeed in approaching outside of that sector might be regarded as flanking. But this is speculative. However, if we think of flanking at sea as achieving an operational level ambush, we can see it exhibited in historic naval campaigns and battles. At Midway, the US task force took a position to the northeast of Midway Island and succeeded in ambushing the Japanese carrier force. In March of 1805 Admiral Horatio Nelson took a “secret position” between Sardinia and Mallorca hoping to ambush Admiral Villenueve’s French fleet if it sailed toward Italy or Egypt. 

Now, in the Midway case, the Japanese forces did not find the American task force until too late and suffered the loss of three aircraft carriers (Hiryu was sunk later, after the US task force had been located). In Nelson’s case the ambush would have worked because Villenueve, even though his orders were to escape the Mediterranean via Gibraltar, had planned to sail east of Mallorca, which would have led him into Nelson’s trap. However, a merchant ship had seen Nelson’s force and reported it to Villenueve, who altered his route to west of Mallorca. If the Japanese had located the American task force earlier, the results of Midway would likely have been much different. Both examples reveal the critical importance of finding first.

Anyone familiar with the writing of legendary Naval Postgraduate School Professor Wayne Hughes’ and his principle of “strike effectively first,” will immediately see the connection with this rule. Getting in an effective first strike requires finding effectively first, and no naval ambush can occur if this does not happen. This in turn requires enemy scouting efforts are ineffective and the enemy commander remains ignorant of the ambushing force. The act of finding and striking effectively first should not be viewed in momentary isolation or as singularly decisive, because command decision-making at all levels will be critical in maneuvering these finding and striking forces prior to successful engagements. So, while the term flanking does not translate well into naval warfare, its implied dependency on maneuver does carry over.

Rule 3: Swarming Always Beats Surging

The third rule is a bit trickier to relate to naval warfare. Arquilla states in the interview that “You don’t need big numbers to swarm the opponent with a lot of small smart weapons.” The implication is that instead of achieving mass or concentration of force using symmetrical weapons, tanks versus tanks, for instance, forces can make asymmetric attacks by using smart weapons not tied to big platforms, i.e., many teams of Javelin shooters versus columns of Russian tanks. In that sense the third rule seems to be merely a restatement of the first. That said, swarming is a term that has taken on new meaning in an age of smart drones. The notion of a large number of small things “besetting” a target conveys Arquilla’s implicit meaning. 

Picking this apart a bit more, let’s regard surging as the assembling of a force or capability that is greater than that of the enemy it is confronting – the traditional concentration of force, either at the operational or tactical level. Swarming, on the other hand, implies coming at a particular enemy target from everywhere, whether the besetting attack is centrally planned or whether it is based on the self-synchronization of the individual swarming entities. Surging implies a numerical relationship between the opposing forces, one presumably outnumbering the other. Swarming involves no such relationship – it is about having enough individual units to beset a target from all sides either simultaneously or in rapid sequence. Swarming seems generally to apply to the tactical, unit or even weapons level.

An instantiation of swarming in naval warfare would involve the use of deception drones or missiles meant to saturate an enemy ship’s defenses. The US Navy devised an elemental form of swarming tactics in its attempt, after the showdown with the Soviet Fleet in the Mediterranean in 1973, to generate some kind of anti-ship capability, which it had let lapse after World War II. The tactic involved a formation of five aircraft approaching the enemy ship at low level. Flying in close formation it would look like one blip on enemy radars. At a certain point the aircraft would starburst, fanning out in different directions and then turning back in based on careful timing such that they would arrive at their bomb release points in rapid succession. The maneuver was meant to confuse the target ship’s fire control systems and at the end saturate defenses such that at least one aircraft would be able to reach its release point. 

Surging implies Lanchestrian calculations that reveal the superiority of numbers; swarming is about creating confusion, using relatively large numbers for sure, but not in the strict relative sense addressed by Lanchester’s equations.1 This point is widely appreciated: China is thought to have developed large numbers of deceptive drones and missile warheads that can deploy decoys to achieve confusion and saturation of US Navy ship defenses.

At the present state of the art, achieving swarming would still require either a large number of launching platforms or engagement from relatively close range.  If the Navy did adopt the concept of a flotilla of smaller missile combatants there would have to be significant covering and deception efforts to get them into position to use their missiles and decoys. On the other hand, cover for a salvo of long range missiles might be provided by long range bombers that could launch decoys in addition to anti-ship missiles. However, the central point is that swarming – no matter how it is achieved – offers potential relief from the brute force logic of Lanchester’s equations.

Taking the Rules to Sea

If we combine Arquilla’s three rules, what do we get in terms of a picture of future naval warfare? First, it would seem that we could articulate a rather more nuanced rule: the force that can find, evaluate and target first will have a significant advantage. However, if both sides forces are composed of smaller, dispersed missile-shooting units, be they surface, air or subsurface, both fleets would likely be more resilient if they had to absorb a first strike. A naval battle would then become a geographically dispersed, cat-and-mouse game of progressive attrition. The game board would include not only the ocean, including the air above, adjacent land features and the depths below, but space, cyberspace and the electromagnetic spectrum. If swarming attacks were fully developed and employed, the only defense would be to avoid detection through stand-off, stealth, or deception.  The set piece naval battle would be replaced by an extended campaign of raids and quick strikes, followed by rapid retreat into sanctuaries or out of range. Knowledge of the tactical and operational situation would be intermittent and mostly fragmentary. The chances of putting together a large and coordinated missile salvo from dispersed units would be small, assuming the enemy is able to disrupt friendly networks in some way, so each unit must be armed with missiles that have the ability to create their own terminal swarms. This would allow for a form of swarming on a larger scale; dispersed units would operate on the basis of mission orders, and a swarming rule set, including a precise definition of calculated risk appropriate to the situation. The operation of German U-boat wolf packs in World War II constituted a nascent form of such a battle.

Neither the formalized collision of lines of dreadnoughts nor the long range groping of carrier battles are likely to characterize future naval warfare. Arquilla’s three rules imply intermittent and dispersed missile-based campaigns of attrition that will extend over days, weeks or even months; the quick and decisive clash at sea could very well be a thing of the past. If this is so, fleet design must be rethought. Missiles, not tactical aircraft dropping bombs, will be the decisive weapons. The Fleet’s offensive power must be distributed among a larger number of platforms, and its doctrine must include ground and long-range air elements. Logistics for such a force that would allow it to remain in contested areas for extended periods must be worked out. Sensing and processing as well as resilient communications will, in effect, become the new “capital ship” of the Navy, as these will allow the offensive missiles to be most effective in accordance with Arquilla’s rules. There will be a continuing need for some residual legacy forces, as the Navy has a multi-faceted and global mission, but for high-end naval combat in littoral waters, a force designed around Arquilla’s rules will be needed in order to fight at acceptable levels of strategic risk.

Does all this have implications for traditional naval concepts like command of the sea and sea control? Almost certainly. Command of the sea has heretofore meant that the weaker navy either could not or would not directly confront the stronger. This allowed the stronger navy to use the seas for its own purposes and deny such use to the weaker. But if sea power becomes atomized, composed of many missile shooting units, then the deterrent basis for command of the sea evaporates. We see a nascent form of this already with the Chinese land-based DF-21 and 26 anti-ship ballistic missiles. While this condition may initially be limited to specific littoral regions, the continued development of naval forces shaped by Arquilla’s rules would imply that command of the sea could be contested by weaker navies farther and farther out at sea, to the point that the concept loses meaning. Sea control, the function of protecting things like merchant traffic or geographic points, would become the paramount concept and demand the utmost in dispersion of forces – strategic, operational and tactical. Thus navies desiring to produce for their nations the traditional benefits of command of the sea would have to be composed of numerous and therefore cheaper units so that naval power would be available at any and all points needed, whenever that need arose.

Chaos theory shows how complex phenomena can emerge from simple rule sets. If we tease out their threads, Arquilla’s three simple rules for new age warfare seem to be able to perform that trick with regards to naval warfare and the design of navies. We might look askance at the categorical tone he uses in those rules, but that should not cause us to dismiss them as new age fluff. Some basis for fleet design is needed beyond the narrow incorporation of the next better radar or aircraft, and these three rules seem to be worth considering in that endeavor.

Robert C. Rubel is a retired Navy captain and professor emeritus of the Naval War College. He served on active duty in the Navy as a light attack/strike fighter aviator. At the Naval War College he served in various positions, including planning and decision-making instructor, joint education adviser, chairman of the Wargaming Department, and dean of the Center for Naval Warfare Studies. He retired in 2014, but on occasion continues to serve as a special adviser to the Chief of Naval Operations. He has published over thirty journal articles and several book chapters.

Endnotes

1. In its simplest form it is Aa2 = Bb2 where A and B equal the quality of the respective forces; a and b represent the number of forces. This reflects the dominance of numbers in calculating the outcome of engagements.

Featured Image: KEKAHA, Hawaii – Artillery Marines from 1st Battalion, 12th Marines escort a Navy Marine Expeditionary Ship Interdiction System launcher vehicle ashore aboard Pacific Missile Range Facility Barking Sands, Hawaii, Aug. 16, 2021. (U.S. Marine Corps photo)

Emerging Tech Week

Responding to the Proliferation of Uninhabited Underwater Vehicles

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Emerging Technologies Topic Week

Sections of the following article are adapted from a forthcoming master’s degree thesis, titled The Hunt for Underwater Drones: Explaining the Proliferation of Uninhabited Underwater Vehicles. 

By Andro Mathewson

In late May 2021, the Israeli armed forces destroyed an armed underwater uninhabited vehicle (UUV)1 operated by the terrorist group Hamas. This kamikaze-UUV was used in an attempt to attack Israeli offshore gas and oil installations, which Hamas had unsuccessfully targeted in the past using rockets and uninhabited aerial vehicles (UAVs). This is possibly the first use of an armed UUV by a non-state actor, but UUVs have been in use since the 1950s, with the United States and Russia leading the charge. UUVs are now owned by over fifty nations across the world. Understanding why and how this technology proliferates is crucial to recognizing the role of such new technologies in international security and preparing effective responses. Based on this common understanding, the international community can counter further UUV proliferation by establishing a framework of norms and agreements, while security forces and military industries can focus on advancing effective counter-UUV technology.

Why Examine the Proliferation of UUVs?

UUVs are becoming an important tool within the realm of international security. Naval forces across the world are quickly developing and acquiring a variety of UUVs due to their furtive nature, dual-use capabilities, and multifaceted functionalities. While the technology is still in relatively early development stages and leaves much to be desired, UUVs have quickly become an integral element of modern navies but also appear in the arsenals of lesser developed armed forces and non-state actors due to their utility as an asymmetric tool for sea denial. With advancements in intelligence gathering, surveillance, and reconnaissance technologies, UUVs are becoming essential assets in the maritime forces of states across the world. Although still predominantly used in an unarmed and surveillance capacity, UUVs have recently also been both adapted and designed to carry explosive ordnance and act in an offensive capacity. While the United States and Russia are at the forefront of UUV development, over fifty other states have either developed or acquired UUVs, as the following map shows.  

Countries in possession of UUVs as of May 2021.2

There is also considerable interest in underwater drones and their diverse applications from militaries, private corporations, civil society organizations, and journalists alike.3 Their broad applications explain why the global UUV market size is projected to grow from USD 2.0 billion in 2020 to USD 4.4 billion by 2025. Despite the increasing interest in UUVs, many commentaries about their proliferation and use are based on speculation rather than on empirical analysis. Finally, examining the early proliferation of UUVs offers opportunities to explore, in-depth, the initial stages of a technology’s adoption by actors in the international arena, make predictions for the future, and prepare effective responses. While several of the patterns identified in this article might not persist moving forwards, it is nonetheless an opportunity to attempt to understand the wider motivations of governments and decision-makers on a global scale, including the role of security alliances, conflict, geography, economics, and international law.

UUV Proliferation

While at least 30 states have the indigenous capacity to manufacture UUVs, at least 55 states own or have previously owned UUVs.4 This demonstrates that there has been significant technology transfer and diffusion between states. UUVs, and the majority of the technologies they incorporate, are fundamentally dual-use, and the export thereof is often restricted by states and allowed only in a very small set of circumstances. For example, in 2009, the Egyptian Navy signed a deal under the United States Foreign Military Sales program for the delivery of  the U.S.-based Columbia Group’s Pluto Plus UUV system, intended primarily for mine identification and destruction. More recently, in 2016, the United States donated two Remus autonomous underwater vehicles to the Croatian Navy to upgrade their countermine capabilities. While the majority of UUV proliferation is based on such authorized transfers between nations and global corporations or domestic development, there have been numerous cases of unwanted UUV technology transfer through smuggling, intellectual theft, and capture.

There are at least four documented cases of UUVs being seized either by nations or non-state actors. Perhaps the most prominent example is that of China seizing a USN UUV in the South China Sea in late 2016. However, this is not how China first acquired UUV technology, yet it is a possibility that the Chinese Navy deconstructed the UUV to understand and reconstruct the technologies within. While China later returned this drone, it had previously been able to smuggle protected American UUV technology via middlemen out of the United States. Other examples include the capture of a US Remus UUV by Houthi forces off the coast of Yemen in 2018, the seizure of an American early-model mine reconnaissance UUV in 2005 by North Korea, and the capture of a Chinese underwater glider by Indonesian fishermen in 2020. While it remains unknown if these captured UUVs were later remodeled to be operational by their new owners, these incidents showcase both a lesser-known method of technology proliferation and an inherent vulnerability of UUVs.

The legal status of UUVs is a factor that has presently had little influence on their proliferation, partially due to their relative novelty in the international arena as well as due to the currently very unclear legal boundaries concerning unmanned underwater vessels. However, due to the ability of regulatory systems and international law to limit said proliferation or direct it solely to allied states, essentially weaponizing both limitation and regulation, this unclarity is unlikely to continue. Additionally, the distinctive ethical character of war at sea generates several novel ethical dilemmas regarding the design and use of UUVs, which have yet to be answered by international law but certainly require attentiveness.

Country Likelihood of UUV Adoption
Romania .886
Libya .812
Chile .780
Slovenia .751
Argentina .692
South Africa .653
Algeria .588
Cyprus .559
Ukraine .553
Iraq .462

 

Keeping track of new government acquisitions of UUV technology is an important first step in developing adequate responses. Thus, looking to the future, the database created for this article and the subsequent analysis thereof can help identify possible future adopters of UUVs.5 While exact foretelling is nigh impossible, the following table lists the ten most likely future adopters of UUV technology based on the author’s model.   The majority of the nations listed have extensive military requirements. As UUVs become less cost-prohibitive and countries become wealthier, their proliferation may reach a tipping point where they become a widespread and almost ubiquitous technology, possibly following the route of UAVs, which are now present in almost every military across the globe. One other possible explanation for the future acquisition of UUVs by these listed states is their involvement in ongoing maritime disputes as UUVs are useful tools for monitoring vessel movements in contested spaces.

Responses to UUV Proliferation

Due to their relative novelty, both responses to their use and mitigation strategies are presently scarce. Countering global UUV proliferation should be an imperative for the United States Navy, its allies, and international organizations alike. Despite the clear recent increase in proliferation over the past decade, there are currently no national or international agencies in charge of a response to military purpose UUVs, while their ambiguous legal status has led to a de-facto underwater arms race. Nevertheless, there are two possible answers to these challenges: risk mitigation and counter-UUV technology. However, a dual-pronged approach addressing both simultaneously will most likely have the most effective results.

The first option relies on a rules-based international system and the adherence of states to international agreements and regulations. Risk mitigation strategies attempt to minimize the risk of conflict through international cooperation. In the case of military technologies, this is primarily via arms control agreements, the effectiveness of which is hotly contested. While arms control has been somewhat effective for several weapons, such as cluster munitions, its ability to restrict the proliferation of other uninhabited vehicles, such as aerial drones, has been generally deemed unsuccessful. Similar to UAVS, the place of UUVs in the international legal framework is highly uncertain. Many issues remain unanswered: Is a UUV part of its state of origin and thus immune from legal seizure by other nations? Should they operate only on the surface in another nation’s territorial seas? Can it legally operate there at all?  (This is only a snippet of the many questions on UUV legality).

Deciding upon the legal status of UUVs in both domestic and international law is crucial for the security of states and the reduction of risk in the international arena. For example, classifying UUVs as ships or extensions thereof would categorize them under the rules of the United Nations Convention on the Law of the Sea (UNCLOS). This would allow UUVs to act correspondingly in the regions of the sea as determined by UNCLOS, illuminating where they may be legally deployed and for what reasons. Within the different zones, states could apply the rules currently affecting maritime vessels to UUVs, restricting the available legal actions of the UUV-controlling state. However, UNCLOS is not inviolable. Amongst many others, the United States has not ratified UNCLOS, reducing its coercive power. Many other states, including Russia and China, often criticize and neglect its stipulations. International law enforcement is also often ineffectual. Thus, although enforcing UUV use under the clauses of UNCLOS could alleviate some tensions, it is far from a panacea. Consequently, states must also develop more reliable defensive strategies and technologies to thwart antagonistic UUV deployments.

The development of counter-UUV technology is in its infancy, primarily due to two factors: the novelty of UUVs and the fact that they are predominantly still unarmed and used mainly for surveillance and intelligence gathering. However, the sooner the United States and its allies invest in and develop effective counter-UUV technologies and strategies, the more prepared they’ll be more future encounters. Due to the dual-use nature of UUVs, the true intentions behind their deployment are almost indistinguishable. Thus, states must prepare an extensive response toolkit, which requires both economic and political investments. Countering a technologically advanced threat requires the development of new defense mechanisms. In the case of UUV’s this could be new countermeasure methods of detection, tracking, and tracking – for example – acoustic or magnetic tripwires, to determine underwater movements through sensitive passages like harbors or straights. Another option is a more aggressive approach, such as the development of new systems to capture or outright destroy UUVs operated by adversarial states, including more precise torpedoes or more advanced naval mines capable of targeting and destroying UUVs.

Conclusion

The current status of aerial drones and their widespread use across the world offers militaries, policymakers, and international organizations the opportunity to prevent a similar scenario from occurring with underwater drones. While UAV technologies come with certain benefits to state military forces, such as surgical precision airstrikes, their indiscriminate use by non-state actors and terrorist groups has wrought havoc across the Middle East. Preventing a similar outcome with the continued proliferation of UUVs is vital to the security of the global ocean and the ships upon it. This will require concerted efforts and significant international cooperation from governments, international organizations, and civil society groups alike. While the successful control of UUV proliferation is not impossible, states must also prepare for the adverse outcome and develop effective and efficient counter-UUV strategies and technologies.

Andro Mathewson is a Research Fellow at the Arctic Institute, a Capability Support Officer at the HALO Trust, and an International Relations MSc student at the University of Edinburgh. His dissertation explores the proliferation of uninhabited underwater vehicles (UUVs) on a global scale. He is interested in international security, military technologies, and naval warfare. Andro has previously contributed to the Bulletin of Atomic Scientists, the Texas National Security Review, the Wavell Room, and the UK Defence Journal. Before his current studies, he was a research fellow at Perry World House at the University of Pennsylvania, where he also received his Bachelor of Arts in PPE and German. The views expressed in this article are those of the author and do not necessarily reflect the official position of The HALO Trust.

Endnotes

1. For the purposes of this article, the term uninhabited underwater vehicles (UUV) will be used throughout. There is no generally accepted nomenclature, thus “UUV” in this paper will encompass all types of uninhabited underwater vehicles, regardless if armed, unarmed, military, civilian, autonomous, or remotely operated. UUVs are also known as underwater drones or undermanned underwater vehicles and include autonomous underwater vehicles (AUVs), remotely operated underwater vehicles (ROUVs), and underwater gliders. However, it is also important to note that this essay focusses exclusively on government owned UUVs.

2. The map illustrates states and their militaries that are in possession of UUVs, regardless if those are armed or not, or how they were acquired (developed, bought, co-owned, transferred, or captured).

3. Part of this is driven by their dual-use nature and multifaceted abilities, including, for example, wreck salvage and environmental survey, as well as by the growing number of deep-water offshore oil & gas production activities and increasing maritime security threats.

4. This data is based on an original cross-sectional database produced in May 2021, containing information on the UUV capabilities of 196 states and 2 non-state actors. I use the term “at-least” for two reasons: (1) Due to the military nature of UUVs, it is safe to assume that there is significant information pertaining to their proliferation that is publicly unavailable, and (2) despite extensive research, there is always the possibility that there are lapses in my data.

5. To analyse this data, I use a probit regression model, focusing on two dependant variables (government UUV ownership and domestic production capacity) and the following independent variables: Access to the global ocean; Ratification of the United Nationals Convention on the Laws of the Sea; Submarine ownership; UAV ownership; NATO membership; Ongoing Maritime Disputes; Military Expenditure; and GDP per capita. This model shows an estimated probability that a state with a set of particular characteristics (the independent variables) will either own UUVs or have the domestic capacity to produce them. Based on this model, the list shows states most likely to acquire UUVs next, compared to the overall characteristics of states already owning UUVs.

Featured Image: Unmanned underwater vehicles, assigned to Commander, Task Group 56.1, are pre-staged before UUV buoyancy testing. (U.S. Navy photo by Mass Communication Specialist 1st Class Julian Olivari/Released)

Future Tech

Winning The AI-Enabled War-at-Sea

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By Dr. Peter Layton

Artificial intelligence (AI) technology is suddenly important to military forces. Not yet an arms race, today’s competition is more in terms of an experimentation race with many AI systems being tested and new research centers established. There may be a considerable first-mover advantage to the country that first understands AI adequately enough to change its existing human-centered force structures and embrace AI warfighting.

In a new Joint Studies Paper, I explore sea, land and air operational concepts appropriate to fighting near-to-medium term future AI-enabled wars. With much of the underlying narrow AI technology already developed in the commercial sector, this is less of a speculative exercise than might be assumed. Moreover, the contemporary AI’s general-purpose nature means its initial employment will be within existing operational level constructs, not wholly new ones.

Here, the focus is the sea domain. The operational concepts mooted are simply meant to stimulate thought about the future and how to prepare for it. In being so aimed, the concepts are deliberately constrained; crucially they are not joint or combined. In all this, it is important to remember that AI enlivens other technologies. AI is not a stand-alone actor, rather it works in the combination with numerous other digital technologies. It provides a form of cognition to these.

AI Overview

In the near-to-medium term, AI’s principal attraction is its ability to quickly identify patterns and detect items hidden within very large data troves. The principal consequence of this is that AI will make it much easier to detect, localize and identity objects across the battlespace. Hiding will become increasingly difficult. However, AI is not perfect. It has well known problems in being able to be fooled, in being brittle, being unable to transfer knowledge gained in one task to another and being dependent on data.

AI’s warfighting principal utility then becomes ‘find and fool’. AI with its machine learning is excellent at finding items hidden within a high clutter background. In this role AI is better than humans and tremendously faster. On the other hand, AI can be fooled through various means. AI’s great finding capabilities lack robustness.

A broad generic overview is useful to set the scene. The ‘find’ starting point is placing a large number of low cost Internet of Things (IoT) sensors in the optimum land, sea, air, space and cyber locations in the areas across which hostile forces may transit. From these sensors, a deep understanding can be gained of the undersea terrain, sea conditions, physical environment and local virtual milieu. Having this background data accelerates AI’s detection of any changes and, in particular, of the movement of military forces across it.

The fixed and mobile IoT edge-computing sensors are connected into a robust cloud to reliably feed data back into remote command support systems. The command system’s well-trained AI could then very rapidly filter out the important information from the background clutter. Using this, AI can then forecast adversary actions and predict optimum own force employment and its combat effectiveness. Hostile forces geolocated by AI can, after approval by human commanders, be quickly engaged using indirect fire including long-range missiles. Such an approach can engage close or deep targets; the key issues being data on the targets and the availability of suitable range firepower. The result is that the defended area quickly becomes a no-go zone.

To support the ‘fool’ function, Uncrewed Vehicles (UV) could be deployed across the battlespace equipped with a variety of electronic systems suitable for the Counter Intelligence Surveillance And Reconnaissance And Targeting (C-ISRT) task. The intent is to defeat the adversary’s AI ‘find’ capabilities. Made mobile through AI, these UVs will be harder for an enemy to destroy than fixed jammers would be. Moreover, mobile UVs can be risked and sent close in to approaching hostile forces to maximize jamming effectiveness. Such vehicles could also play a key role in deception, creating a false and misleading impression of the battlefield to the adversary. Imagine a battlespace where there are a thousand ‘valid’ targets, only a few of which are real.

A War-at-Sea Defense Concept

Defense is the more difficult tactical problem during a war-at-sea. Its intent is solely to gain tactical time for an effective attack or counterattack. Wayne Hughes goes as far in his seminal work to declare that: “All fleet operations based on defensive tactics…are conceptually deficient.”1  The AI-enabled battlefield may soften this assertion.

Accurately determining where hostile ships are in the vast ocean battlefields has traditionally been difficult. A great constant of such reconnaissance is that there never seems to be enough. However, against this, a great trend since the early 20th century is that maritime surveillance and reconnaissance technology is steadily improving. The focus is now not on collecting information but on improving the processing of the large troves of surveillance and reconnaissance data collected.2 Finding the warship ‘needle’ in the sea ‘haystack’ is becoming easier. 

The earlier generic ‘find’ concept envisaged a large distributed IoT sensor field. Such a concept is becoming possible in the maritime domain given AI and associated technology developments.

DARPA’s Ocean of Things (OoT) program aims to achieve maritime situational awareness over large ocean areas through deploying thousands of small, low-cost floats that form a distributed sensor network. Each smart float will have a suite of commercially available sensors to collect environmental and activity data; the later function involves automatically detecting, tracking and identifying nearby ships and – potentially – close aircraft traffic. The floats use edge processing with detection algorithms and then transmit the semi-processed data periodically via the Iridium satellite constellation to a cloud network for on-shore storage. AI machine learning then combs through this sparse data in real time to uncover hidden insights. The floats are environmentally friendly, have a life of around a year and in buys of 50,000 have a unit cost of about US$500 each. DARPA’s OoT shows what is feasible using AI.

In addition to floats, there are numerous other low-cost AI-enabled mobile devices that could noticeably expand maritime situational awareness including: the EMILY Hurricane Trackers, Ocean Aero Intelligent Autonomous Marine Vehicles, Seaglider Autonomous Underwater Vehicles, Liquid Robotics Wave Gliders and Australia’s Ocius Technology Bluebottles.

In addition to mobile low-cost autonomous devices plying the seas there is an increasing number of smallsats being launched by governments and commercial companies into low earth orbit to form large constellations. Most of these will use AI and edge computing; some will have sensors able to detect naval vessels visually or electronically.

All this data from new sources can be combined with that from the existing large array of traditional maritime surveillance systems. The latest system into service is the long-endurance MQ-4C Triton uncrewed aerial vehicle with detection capabilities able to be enhanced through retrofitting AI. The next advance may be the USN’s proposed 8000km range, AI-enabled Medium Unmanned Surface Vessel (MUSV) which could cruise autonomously at sea for two months with a surveillance payload.

With so many current and emerging maritime surveillance systems, the idea of a digital ocean is becoming practical. This concept envisages the data from thousands of persistent and mobile sensors being processed by AI, analyzed though machine learning and then fused into a detailed ocean-spanning three-dimensional comprehensive picture. Oceans remain large expanses making this a difficult challenge. However, a detailed near-real time digital model of smaller spaces such as enclosed waters like the South China Sea, national littoral zones or limited ocean areas of specific import appears practical using current and near-term technology.

Being able to create a digital ocean model may prove revolutionary. William Williamson of the USN Naval Postgraduate School declares: “On the ‘observable ocean’, the Navy must assume that every combatant will be trackable, with position updates occurring many times per day. …the Navy will have lost the advantages of invisibility, uncertainty, and surprise. …Vessels will be observable in port…[with] the time of departure known to within hours or even minutes. This is true for submarines as well as for surface ships.”3

This means that in a future major conflict, the default assessment by each warship’s captain might be that the adversary probably knows the ship’s location. Defense then moves from being “conceptually deficient” to being the foundation of all naval tactics in an AI-enabled battlespace. The emerging AI-enabled maritime surveillance system of systems will potentially radically change traditional war-at-sea thinking. The ‘attack effectively first’ mantra may need to be rewritten to ‘defend effectively first.’

The digital, ‘observable ocean’ will ensure warships are aware of approaching hostile warships and a consequent increasing risk of attack. In this addressing this, three broad alternative ways for the point defense of a naval task group might be considered.

Firstly, warships might cluster together, so as to concentrate their defensive capabilities and avoid any single ship being overwhelmed by a large multi-axis, multi-missile attack. In this, AI-enabled ship-borne radars and sensors will be able to better track incoming missiles amongst the background clutter. Moreover, AI-enabled command systems will be able to much more rapidly prioritize and undertake missile engagements. In addition, nearby AI-enabled uncrewed surface vessels may switch on active illuminator radars, allowing crewed surface combatants to receive reflections to create fire control-quality tracks. The speed and complexity of the attacks will probably mean that human-on-the-loop is the generally preferred AI-enabled ship weapon system control, switching to human-out-of-the-loop as numbers of incoming missiles rise or hypersonic missiles are faced.

Secondly, instead of clustering, warships might scatter so that an attack against one will not endanger others. Crucially, modern technology now allows dispersed ships to fight together as a single package. The ‘distributed lethality’ concept envisages distant warships sharing precise radar tracking data across a digital network, although there are issues of data latency that limit how far apart the ships sharing data for this purpose can be. An important driver of the ‘distributed lethality’ concept is to make adversary targeting more difficult. With the digital ocean, this driver may be becoming moot.

Thirdly, the defense in depth construct offers new potential through becoming AI-enabled, particularly when defending against submarines although the basic ideas also have value against surface warship threats. In areas submarines may transit through, stationary relocatable sensors like the USN’s Transformational Reliable Acoustic Path System could be employed backed up by unpowered, long endurance gliders towing passive arrays. These passive sonars would use automated target recognition algorithms supported by AI machine learning to identify specific underwater or surface contacts.

Closer to the friendly fleet, autonomous MUSVs could use low-frequency active variable depth sonars supplemented by medium-sized uncrewed underwater vehicles (UUV) with passive sonar arrays. Surface warships or the MUSVs could further deploy small UUVs carrying active multistatic acoustic coherent sensors already fielded in expendable sonobuoys. Warships could employ passive sonars to avoid counter-detection and take advantage of multistatic returns from the active variable depth sonars deployed by MUSVs.

Fool Function. The “digital ocean” significantly increases the importance of deception and confusion operations. This ‘fool’ function of AI may become as vital as the ‘find’ function, especially in the defense. In the war-at-sea, the multiple AI-enabled systems deployed across the battlespace offer numerous possibilities for fooling the adversary.

Deception involves reinforcing the perceptions or expectations of an adversary commander and then doing something else. In this, multiple false cues will need seeding as some clues will be missed by the adversary and having more than one will only add to the deception’s credibility. For example, a number of uncrewed surface vessels could set sail as the warship leaves port, all actively transmitting a noisy facsimile of the warships electronic or acoustic signature. The digital ocean may then suggest to the commander multiple identical warships are at sea, creating some uncertainty as to which is real or not.

In terms of confusion, the intent might be not to avoid detection as this might be very difficult but instead prevent an adversary from classifying vessels detected as warships or identifying them as a specific class of warship. This might be done using some of the large array of AI-enabled floaters, gliders, autonomous devices, underwater vehicles and uncrewed surface vessels to considerably confuse the digital ocean picture. The aim would be to change the empty oceans – or at least the operational area – into a seemingly crowded, cluttered, confusing environment where detecting and tracking the real sought-after warships was problematic and at best fleeting. If AI can find targets, AI can also obscure them.

A War-at-Sea Offense Concept

In a conflict where both sides are employing AI-enabled ‘fool’ systems, targeting adversary warships may become problematic. The ‘attack effectively first’ mantra may evolve to simply ‘attack effectively.’ Missiles that miss represent a significant loss of the task group’s or fleet’s net combat power, and take a considerable time to be replaced. Several alternatives may be viable.

In a coordinated attack, the offence might use a mix of crewed and uncrewed vessels. One option is to use three ship types: a large, well-defended crewed ship that carries considerable numbers of various types of long-range missiles but which remains remote to the high-threat areas; a smaller crewed warship pushed forward into the area where adversary ships are believed to be both for reconnaissance and to provide targeting for the larger ship’s long-range missiles; and an uncrewed stealthy ship operating still further forward in the highest risk area primarily collecting crucial time-sensitive intelligence and passing this back through the smaller crewed warship onto the larger ship in the rear.

The intermediate small crewed vessel can employ elevated or tethered systems and uncrewed communications relay vehicles to receive the information from the forward uncrewed vessel and act as a robust gateway to the fleet tactical grid using resilient communications systems and networks. Moreover, the intermediate smaller crewed vessel in being closer to the uncrewed vessel will be able to control it as the tactical situation requires and, if the context changes, adjust the uncrewed vessel’s mission.

This intermediate ship will probably also have small numbers of missiles available to use in extremis if the backward link to the larger missile ship fails. Assuming communications to all elements of the force will be available in all situations may be unwise. The group of three ships should be network enabled, not network dependent, and this could be achieved by allowing the intermediate ship to be capable of limited independent action.

The coordinated attack option is not a variant of the distributed lethality concept noted earlier. The data being passed from the stealthy uncrewed ship and the intermediate crewed vessel is targeting, not fire control, quality data. The coordinated attack option has only loose integration that is both less technically demanding and more appropriate to operations in an intense electronic warfare environment.

An alternative concept is to have a large crewed vessel at the center of a networked constellation of small and medium-sized uncrewed air, surface and subsurface systems. A large ship offers potential advantages in being able to incorporate advanced power generation to support emerging defensive systems like high energy lasers or rail guns. In this, the large crewed ship would need good survivability features, suitable defensive systems, an excellent command and control system to operate its multitude of diverse uncrewed systems and a high bandwidth communication system linking back to shore-based facilities and data storage services.

The crewed ship could employ mosaic warfare techniques to set up extended kinetic and non-kinetic kill webs through the uncrewed systems to reach the adversary warships. The ship’s combat power is not then in the crewed vessel but principally in its uncrewed systems with their varying levels of autonomy, AI application and edge computing.

The large ship and its associated constellation would effectively be a naval version of the Soviet reconnaissance-strike complex.  An AI-enabled war at sea then might involve dueling constellations, each seeking relative advantage.

Conclusion

The AI-enabled battlespace creates a different war-at-sea. Most obvious are the autonomous systems and vessels made possible by AI and edge computing. The bigger change though may be to finally take the steady scouting improvements of the last 100 years or so to their final conclusion. The age of AI, machine learning, big data, IoT and cloud computing appear set to create the “observable ocean.” From combining these technologies, near-real digital models of the ocean environment can be made that highlight the man-made artefacts present.

The digital ocean means warships could become the prey as much as the hunters. Such a perspective brings a shift in thinking about what the capital ship of the future might be. A recent study noted: “Navy’s next capital ship will not be a ship. It will be the Network of Humans and Machines, the Navy’s new center of gravity, embodying a superior source of combat power.” Tomorrow’s capital ship looks set to be the human-machine teams operating on an AI-enabled battlefield.

Dr. Peter Layton is a Visiting Fellow at the Griffith Asia Institute, Griffith University and an Associate Fellow at the Royal United Services Institute. He has extensive aviation and defense experience and, for his work at the Pentagon on force structure matters, was awarded the US Secretary of Defense’s Exceptional Public Service Medal. He has a doctorate from the University of New South Wales on grand strategy and has taught on the topic at the Eisenhower School. His research interests include grand strategy, national security policies particularly relating to middle powers, defense force structure concepts and the impacts of emerging technology. The author of ‘Grand Strategy’, his posts, articles and papers may be read at: https://peterlayton.academia.edu/research.

Endnotes

1. Wayne P. Hughes and Robert Girrier, Fleet tactics and naval operations, 3rd edn., (Annapolis: Naval Institute Press, 2018), p. 33.

2. Ibid., pp.132, 198.

3. William Williamson, ‘From Battleship to Chess’, USNI Proceedings, Vol. 146/7/1,409, July 2020, https://www.usni.org/magazines/proceedings/2020/july/battleship-chess

Featured image: Graphic highlighting Fleet Cyber Command Watch Floor of the U.S. Navy. (U.S. Navy graphic by Oliver Elijah Wood and PO2 William Sykes/Released)