Tightening the Chain: Implementing a Strategy of Maritime Pressure in the Pacific

The following is adapted from a recent report by the Center for Strategic and Budgetary Assessments, Tightening the Chain: Implementing a Strategy of Maritime Pressure in the Western Pacific.

By Peter Kouretsos

The U.S. military has a problem in the Western Pacific: the tyranny of distance and time. Delivering military force across the vast Pacific Ocean has never been easy, even for a country as blessed in resources and ingenuity as the United States. The problem has worsened as America’s chief regional rival, China, has improved its ability to harm American interests quickly and with limited forewarning. Seventy years after Mao Zedong proclaimed the People’s Republic of China, China’s military capabilities have matured to the point where, if directed by the Chinese Communist Party (CCP), the People’s Liberation Army (PLA) could launch a rapid attack to change the status quo, including territorial seizure, before the United States could meaningfully respond, thus presenting Washington with a fait accompli. American forces located outside the conflict area would have to penetrate China’s anti-access/area-denial (A2/AD) network to restore the status quo ex-ante, a daunting proposition. Under these circumstances, Washington might face the unenviable choice of doing nothing or escalating to higher levels of violence. Either way, the national interests of both the United States and its closest allies would suffer dramatically.

To address this challenge, a new CSBA report proposes a U.S. military strategy of Maritime Pressure and a supporting joint operational concept, “Inside-Out” Defense, to stabilize the military balance in the Western Pacific and deny China the prospect of a successful fait accompli. The report goes beyond previous studies by outlining a new operational concept, assessing potential Chinese responses, and estimating the budgetary costs of implementing it.

Strategy in Brief

The United States faces a geographic asymmetry in the Western Pacific. China’s primary territorial concerns—Taiwan, the South China Sea, and the East China Sea—are far closer to its mainland than they are to the United States. In contrast, the United States has territory, allies, and interests in the Western Pacific but must traverse the expanse of the Pacific Ocean to defend them. At the same time, the PLA has developed a counter-intervention doctrine and supporting A2/AD capabilities to stifle the U.S. military’s ability to project power rapidly into, or operate effectively within, the Western Pacific during a conflict. Given these challenges, the United States would be hard-pressed to overcome the tyranny of distance and Chinese A2/AD capabilities quickly enough to deny a Chinese fait accompli.

For example, in the direst scenario involving an all-out PLA attack on Taiwan, U.S. and allied military forces would have to respond in force quickly, within hours or days, to thwart a Chinese fait accompli attempt. U.S. and allied forces would not have weeks or months to concentrate in mass near the theater of operations and then counterattack before China seizes control of Taiwan or forces the Taiwanese government into submission. Nor would friendly forces have time to fight their way to decisive points in the battlespace if they begin the conflict outside China’s A2/AD bubble. Moreover, attempting to rollback Chinese gains and liberate Taiwan after the fact would be difficult, costly, and potentially escalatory.

American policymakers are right to worry about such a scenario. History shows that deterrence is more likely to fail when an aggressor believes it can pull off a fait accompli successfully. If Chinese leadership believes it can achieve gains through aggression quickly and without paying steep costs in blood, treasure, and reputation, it may be tempted to escalate a crisis to open conflict.

As a deterrence by denial strategy, Maritime Pressure aims to persuade Chinese leaders that attempting military aggression in the Western Pacific will fail, thus discouraging them from trying it. The strategy uses the geography of the First Island Chain—the barrier formed by Japan, Taiwan, the Philippines, and maritime and peninsular Southeast Asia—to deny Chinese military supremacy within, and constrain China’s access beyond, the Western Pacific during crisis or war. Specifically, it aims to thwart Chinese sea control, air superiority, and information dominance, conditions viewed by Chinese leaders as essential to military victory, in order to reduce the Chinese leadership’s confidence in its ability to control the course and outcome of a future conflict, thus bolstering deterrence. In short, by creating doubt in the minds of Chinese leaders about the prospects of a fait accompli gambit, Maritime Pressure discourages them from attempting it in the first place.

As a defense-oriented denial strategy, Maritime Pressure can complement or substitute for alternative approaches such as blockade operations or punishment strikes against mainland China. Those alternatives, although potentially useful as part of a broader campaign to prevail in a protracted conflict with China, would likely not achieve success rapidly enough to thwart a fait accompli, and could escalate the conflict beyond the risk tolerances of U.S. and allied political leaders. Without a strategy designed to prevent a fait accompli, the United States might lose a war before alternative approaches have time to be effective. At a minimum, Maritime Pressure could buy the United States and its allies time, creating the space for other approaches to take effect.

Inside-Out Defense as a Point of Departure Operational Concept

A strategy of Maritime Pressure requires a supporting operational concept that can balance the need to respond rapidly enough to offset the U.S. military’s time-distance challenge without having to physically concentrate U.S. forces on a small number of large, close-in bases that are highly vulnerable to China’s robust area denial capabilities. That is, the operational concept must allow the U.S. military to create the virtues of mass rapidly without the vulnerabilities of concentration.

Inside-Out Defense combines lethal and resilient “inside” forces able to fight and persist within highly contested environments with agile “outside” forces capable of fighting from standoff distances or penetrating A2/AD networks. Together, these inside and outside forces could create a responsive, yet survivable, forward defense-in-depth in the Western Pacific capable of rapidly blunting Chinese aggression at the outset of a conflict. To use a football analogy, the inside forces would act as a defensive line while the outside air and naval forces acted as linebackers. While China may control the snap count, the “Inside-Out Defense” concept will demonstrate that the U.S. is ready to play.

Figure 1: Inside-Out Defense Overview (CSBA Graphic)

Inside forces: Below the level of armed conflict, inside forces forward postured in the Western Pacific would provide a persistent, combat credible signal of U.S. commitment, which should give Chinese leaders pause by complicating their decision calculus and undermining their confidence in their military plans. In the event of conflict, they would exploit the region’s maritime geography and assume a dispersed, resilient posture along the First Island Chain to form an initial defensive barrier that could immediately challenge Chinese military operations and play three key roles. First, they would contest what Chinese doctrine has identified as necessary prerequisites for conducting a successful military campaign: air superiority, sea control, and information dominance. Second, they would attack Chinese power projection forces to delay and deny their ability to achieve objectives through aggression, such as seizing the territory of U.S. allies or partners, while blocking China from projecting power beyond the First Island Chain. Third, they would degrade key Chinese systems to create gaps in China’s A2/AD networks that outside forces could then exploit.

Mobile and dispersed ground forces—and amphibious forces ashore—would form the backbone of these inside forces. Leveraging the inherent survivability of mobile, hard-to-find ground forces augmented with counter-detection aids, such as camouflage, concealment, and deception (CCD), the inside forces would transform the First Island Chain’s archipelagos into defensive bastions bristling with multi-domain capabilities such as sensors, missiles, and electronic warfare systems. Undersea platforms, both manned and unmanned, could operate within or near the East China Sea and South China Sea to augment these island bastions as part of the inside forces.

Outside forces: Primarily consisting of air and naval surface forces, outside forces would provide a flexible and agile element to support the units arrayed along the First Island Chain. The overwhelming mass of U.S. combat power would reside in these outside forces. In the event of conflict, they would back up the defensive barrier and provide defense-in-depth in the Second Island Chain. If necessary, they could surge forward to plug any gaps in the defensive barrier of inside forces created either by lack of U.S. access to allied or partner territory or through attrition from Chinese attacks. By employing standoff and penetrating capabilities, these outside forces could exploit gaps in the Chinese A2/AD complex created by the inside forces in order to augment defensive operations with additional mass and conduct offensive operations. Outside forces could also leverage their greater freedom of maneuver to conduct other priority missions, such as holding Chinese overseas assets at risk or interdicting Chinese maritime commerce.

Lines of Operation

Sea denial: From distributed positions along the First Island Chain, ground forces equipped with launchers capable of firing ASCMs or anti-ship ballistic missiles (ASBMs) could attack Chinese surface ships, creating gaps in China’s outer defenses that outside air and surface forces could then exploit. Undersea forces, including both manned and unmanned platforms, could augment inside ground forces by acting as forward sensors and conducting torpedo and ASCM strikes against Chinese ships, as well as provide the principal method of defeating Chinese undersea forces within the First Island Chain. Surface combatants, 4th generation fighters, and legacy bombers, operating over ground-based air defense bubbles along the First Island Chain, could also support sea denial operations with long-range ASCMs. Other stealthy platforms could operate forward to conduct maritime strikes and act as sensors for land-based missiles. Equipping distributed ground forces with a family of missiles with greater ranges than ones they currently possess (Figure 2) would hedge against more restrictive access for U.S. forces on allied and partner territory, enable ground forces to attack PLAN forces operating closer to China and in the Taiwan Strait, and provide more robust fields of overlapping anti-ship fires.

Figure 2: Overlapping Coverage of Ground-Based Sea-Denial Systems1 (CSBA graphic)

Air denial: Given the long operating distances from airbases primarily located in the Second Island Chain and beyond, U.S. and coalition forces would not be able to continuously contest air superiority in the conflict area. An improved land-based integrated air and missile defense (IAMD) architecture positioned along the archipelagoes of the First Island Chain could help pick up the slack. It would consist of a layered defense of mobile, long-range, wide-area, and short-range point air defense systems employing a mix of missiles, guns, and directed energy capabilities such as lasers and high-power microwaves. Additionally, ISR platforms and fighters partially sheltered behind land-based integrated air defense systems on the First Island Chain could enhance battlespace awareness and plug limited gaps in the air defense perimeter. Penetrating manned and unmanned fighters could also conduct periodic sweeps to contest Chinese air operations.

Information denial: The PLA views information dominance as the most critical condition necessary for victory. As such, counter-C4ISR and information denial operations could have outsized effects in deterring and, if necessary, defeating Chinese aggression. Information denial operations would focus on complicating Chinese ISR, increasing demands for persistent targeting, disrupting communications networks, and ultimately paralyzing China’s centralized decision making. Both inside and outside forces could employ a variety of land-attack, anti-ship, and anti-air weapons to strike Chinese sensors and key nodes to degrade its C4ISR networks. Forces employing electronic warfare, counter-space, and cyber capabilities, augmented by CCD and tactical mobility, could confuse remaining sensors, degrade communications, and overwhelm Chinese information processing and decision-making.

Land attack: Land attack operations would degrade Chinese land-based A2/AD systems—including command and control nodes, sensors, long-range missile launchers, aircraft on the ground, and SAM systems—to create gaps that outside forces could exploit. As with sea denial operations, land-based strikes could be augmented by land-attack cruise missile strikes delivered by submarines, outside air and naval forces conducting standoff attacks with long-range missiles, and stealth aircraft staging attacks from closer in. Now unconstrained by the INF Treaty, the U.S. could regain land-based long-range strike capabilities, forcing China to devote more resources to air and missile defenses. Although not always cost-effective for delivering large salvos, they have considerable value in promptly striking time-sensitive targets such as aircraft on the ground, missile launchers, massed formations, capital ships in port, and critical C4ISR nodes.

Figure 3: Land-Based Long-Range Strike2 (CSBA graphic)

Preserving C4ISR: Attacking China’s C4ISR architecture alone would be insufficient to gain and maintain allied information advantage in a Western Pacific contingency. The U.S. military would also need to preserve friendly C4ISR in the face of Chinese counter-C4ISR capabilities. The U.S. military should thus seek to improve the resiliency of its C4ISR architecture to mitigate the impact of Chinese attacks. But given China’s vast and sophisticated counter-C4ISR capabilities, the U.S. military likely could not prevent disruption or even temporary denial of its networks. Therefore, the U.S. military must be careful not to build an overly centralized theater battle network that must be protected from any significant degradation to function. Rather, the U.S. military should accept that highly contested and degraded information environments will be the norm in future warfare. As such, the U.S. military should develop a C4ISR architecture built for sub-optimal conditions that leverages the inherent strength of the joint force to overcome adversity. In short, the U.S. military should confront China’s highly centralized system designed to operate under the optimal conditions of information dominance with a more resilient U.S. C4ISR system able to continue fighting despite the chaos of the modern battlefield.

Defending forces and bases: Since U.S. forces cannot perfectly hide or defend against China’s planned precision strikes, they must withstand the initial salvo. Hardening key nodes such as communications hubs, fuel stores, and aircraft shelters would help improve resiliency and increase the number of Chinese munitions required to suppress targets. Dispersal of ground and air forces to numerous locations along the First and Second Island Chains would minimize the loss of any large single location. Properly networked, these positions would be mutually reinforcing. Adopting an air defense concept focused on short-and medium-range (10–30 nm) engagements could give defenders greater capacity at less cost. Mobile, distributed launchers such as HIMARS and trailer-mounted containerized launchers would practice disaggregation, tactical mobility, and CCD while operating under IAMD to degrade enemy targeting.

Figure 4: Measures to Improve Resiliency of Inside Forces (CSBA graphic)

Sustaining forces: Inside-Out Defense would require sustaining highly geographically distributed forces operating in austere environments, all while under attack. Ground forces arrayed along the archipelagos of the First Island Chain would leverage pre-positioned stocks of munitions and supplies. Later, combinations of small air and sea assets could work together to resupply and add mobility to these small, dispersed formations. For example, in the near term, offshore support vessels could provide logistical support. In the future, extra-large UUVs—with a payload capacity of 2,000 cubic feet—could transport roughly eight tons of cargo to units operating near the coastline.3 Unmanned surface vessels and dracones could provide additional attritable cargo transport and refueling capabilities. From the air, rotary wing and tactical transport aircraft could operate from austere airfields and sea bases to transport cargo and assist with moving troops.

Recommendations and Costs

Having outlined the Inside-Out Defense concept, CSBA also assessed the current activities of U.S. and allied forces to illuminate where changes are needed most urgently. The report divided the assessment and recommendations into concepts, capabilities, and coordination to reflect Maritime Pressure’s emphasis on the United States pursuing countermoves in the areas of doctrine, technology, and allies, respectively.4 The report estimates that these actions would cost from $8 billion to $13 billion by 2024 depending on the specific investments selected by DoD. Although significant, such costs are affordable—especially if DoD spends less on legacy forces unsuited to contested environments and spends more on the innovative concepts and capabilities proposed in the report.


Develop this report’s approach into a joint operational concept to support a strategy of Maritime Pressure in the Western Pacific. Over the last several years, the Army, Navy, Marine Corps, and Air Force have developed new warfighting concepts that fit comfortably within a strategy of Maritime Pressure. While the Army’s Multi-Domain Operations, Navy’s Distributed Maritime Operations and Marine Corps’ Marine Corps Operating Concept, and the Air Force’s Multi-Domain Command and Control each break some new ground, the services still devote too much attention to preserving the traditional American approach to power projection in the Western Pacific. Furthermore, service concept development efforts are relatively disjointed and uncoordinated from one another, and joint operational concept development is currently lacking within DoD.

Experiment with new organizational structures for ground forces in the Pacific. Given that it is forward stationed in the Western Pacific, III MEF and its subordinate units could form the core of the inside forces in an Inside-Out Defense concept. III MEF would also likely need to be augmented as inside forces with U.S. Army units located in the Pacific Theater such as the 25th Infantry Division. However, both formations are maneuver warfare-centric organizations best suited for traditional amphibious or ground combat operations. The Marine Corps and Army should experiment with alternative force designs that take advantage of novel combinations of C2, fires, air defense, security, ISR, engineering, electronic warfare, and sustainment capabilities to permit distributed, multi-domain fires in highly contested environments along the First Island Chain.

Develop sustainment concepts to support a Maritime Pressure strategy. Supporting distributed operations along the First Island Chain requires new concepts for sustaining operations across great distances while under attack. Planners should explore innovative approaches to support distributed units, including greater use of pre-positioned stocks of munitions and sustainment materiel, manned and unmanned air and sea assets for mobility and resupply, and emerging technologies such as 3D printing to fabricate replacement parts.


Accelerate fielding of mobile, land-based, long-range missile capabilities. Ground force contributions to sea denial, air denial, and land attack operations along the First Island Chain require sharper and longer teeth. Current efforts of the Army and Marine Corps to develop and field longer-range, land-based anti-ship and land-attack fires should be accelerated and should incorporate weapons with ranges in excess of 500 km. The Army and Marine Corps should also develop more mobile and longer-range land-based air defense systems to provide wide-area air denial along the First Island Chain with sufficient survivability for inside forces to fight and persist within China’s A2/AD network.

Build a resilient multi-domain C4ISR architecture and develop and field counter-C4ISR capabilities. In a future conflict in the Western Pacific, the battle for information advantage would likely be critical and could potentially prove decisive. The U.S. military should undertake efforts to make its C4ISR architecture more resilient while developing and fielding active and passive counter-C4ISR capabilities such as jammers and CCD.

Integrate all bomber aircraft with payloads for offensive maritime missions. DoD should integrate anti-ship missiles into its entire fleet of bombers. Although anti-surface warfare would be a new mission for these platforms, it would be a return to a role the bomber community played during World War II and the Cold War. These capabilities are currently being fielded with several aircraft such as the B-1B, but integrating them with all platforms possessing comparable ranges would give the United States a more robust capability to attack enemy surface combatants and other high-value maritime targets in highly contested environments at range.


Deepen cooperation with Indo-Pacific allies and partners. Allies and partners will be critical in a Maritime Pressure strategy, both in terms of accessing their territory and the capabilities and forces they contribute. The U.S. military should engage closely with Indo-Pacific allies and partners to form enhanced access agreements for both peacetime and war, as well as gain a better understanding of what roles each ally and partner may be willing to perform and with what forces in each potential contingency. The U.S. military should also work to deepen interoperability and developed combined concepts of operations among U.S. and allied and partner forces, particularly with Japan and Australia.

Reexamine Service roles and missions. As new concepts for warfighting in the Western Pacific continue to mature, so too should existing Service roles and missions. For example, Inside-Out Defense envisions both Army and Marine forces playing a larger role in anti-surface warfare missions. But key questions remain, such as whether they would provide similar or distinct capabilities for those missions and whether they would perform the missions in separate or overlapping geographic areas. Answering questions like these will help harmonize ongoing efforts to develop new concepts and capabilities across the services.


Attempting to overcome these American A2/AD investments will likely push China toward prioritizing short-range counter-A2/AD improvements over long-range power projection investments. Such an outcome would appeal to the United States and its allies since it would keep China ensnared in its maritime backyard within the First Island Chain. Alternatively, China might view popping the American A2/AD bubble as too risky and expensive and, as a result, shift attention and resources away from its eastern maritime frontier to its western land frontier. President Xi Jinping has increased Chinese involvement in continental Asia through his Belt and Road Initiative, so Maritime Pressure might reinforce an existing preference within the Chinese government for westward expansion. On the negative side, Maritime Pressure might encourage China to escalate horizontally by shifting the competition to other domains, including the economic or diplomatic spheres. Despite this risk, a Maritime Pressure strategy represents a feasible, affordable, and sophisticated approach for responding to China’s rise in the years ahead.

Peter Kouretsos is an Analyst at the Center for Strategic and Budgetary Assessments. He is the co-author, with Thomas G. Mahnken, Travis Sharp, and Billy Fabian, of Tightening the Chain: Implementing a Strategy of Maritime Pressure in the Western Pacific.


1. Ranges and their proxies in parentheses serve as examples, not as specific recommendations. With additional cooperation from partner governments, similar systems could also be placed elsewhere (e.g., Vietnam and Indonesia). NSM, Type-12, and SM-6 ranges are from IHS Jane’s. PrSM range is from Jen Judson, “U.S. Army to Prioritize Long-Range Missile Capability to Go After Maritime Targets,” Defense News, March 26, 2019, available at https://www.defensenews.com/digital-show-dailies/global-force-symposium/2019/03/26/army-to-prioritize-long-range-missile-capability-to-go-after-maritime-targets/. LRASM range is from Oriana Pawlyk, “Live LRASM Test from F/A-18 Super Hornet Expected This Year,” DoDBuzz, April 10, 2018, available at https://www.military.com/dodbuzz/2018/04/10/live-lrasm-test-f-18-super-hornet-expected-year.html. Tomahawk range is from “Tomahawk Cruise Missile,” U.S. Navy factsheet, April 26, 2018, available at www.navy.mil/navydata/fact_display.asp?cid=2200&tid=1300&ct=2.

2. Past CSBA wargames used a notional target set depicting the depth and concentration of Chinese military facilities, mobile weapons systems, airbases, and other sites of military value. Approximately 70 percent of the target set’s 50,000 aimpoints are located within 250 nm of the coastline of mainland China. The deepest aimpoints (red circles) indicate locations of known or suspected space installations, anti-satellite weapons sites, and other high-value targets.

3. The United States only intercepts 25 percent of the homemade submarines carrying narcotics across the Caribbean into the United States from Colombia. Logisticians should incorporate lessons gleaned from these smuggling operations into future sustainment concepts for heavily monitored and contested environments. Joe Gould and David B. Larter, “In America’s Opioid Crisis, Military Lets Drug Shipments Go By,” Defense News, February 15, 2018, available at https://www.defensenews.com/congress/2018/02/16/in-americas-opioid-crisis-military-lets-drug-shipments-go-by/

4. The current activities assessment is limited primarily to the missiles and sensors the authors recommend fielding in precision-strike networks along the First Island Chain. The authors acknowledge that the networks would contain many capabilities besides missiles and sensors. They also recognize that prevailing against China will require more than precision-strike networks. Previous CSBA research has explored other necessary capabilities in detail; interested readers should consult those studies for more information. For the present section, however, the authors have chosen to focus on the strike forces forming the backbone of a Maritime Pressure strategy.

Featured Image: A Japan Ground Self-Defense Force Type 12 Surface to Ship Missile System display its range of movement as part of the Orient Shield 2019 media day, Sept. 17 2019, Oyanohara Training Area, Japan. (U.S. Army Photo by Staff Sgt. Jacob Kohrs, 20th PAD)

With One Hand Tied: Naval Auxiliaries and Their Ability to Conduct Belligerent Acts

By David T. Lee


It is an oft-repeated axiom of international law that vessels which serve as auxiliaries to a state’s armed forces may not lawfully commit a belligerent act in an international armed conflict. The presence of civilian personnel aboard many auxiliaries (including those employed by the U.S. Navy) raise law of war rules governing the use of civilian personnel in armed conflict. But why should ship type – particularly auxiliaries – be a factor in assessing the lawfulness of committing belligerent acts? Instead, it should be considered they be able to do so in the same manner as warships.

Warship or Auxiliary?

The similarities between warships and naval auxiliaries are striking. Naval auxiliaries are vessels under exclusive military control for non-commercial service. Both warships and naval auxiliaries are led by a person subject to the orders or direction of a military chain of command, to potentially include a geographic combatant commander, Navy component commander, or a task force commander. Even with recognizing the different statuses of individuals serving aboard naval auxiliaries, personnel aboard both types of vessels typically may incur some degree of adverse administrative, civil, and disciplinary measures from the military for any failure to follow those orders. While there are nuances in how governments may acquire vessels for the exclusive use of its military forces, some of which may include time-chartered or voyage-chartered vessels, all naval auxiliaries share a warship’s right to exercise sovereign immunity because both conduct only non-commercial government service. Finally, both are lawful military targets in international and non-international armed conflicts, regardless of whether the ship is manned by uniformed military personnel or civilians. Yet despite being subject to hostile attacks, naval auxiliaries may only lawfully act in self-defense.

The limitation imposed on naval auxiliaries makes little sense and has important operational implications. It harkens to an earlier era seeking to protect unarmed mariners. But with the targeting leash loosened, the desire or need to impose legal restrictions on ships based on how they contribute to the fight is unclear. Until the rule changes, U.S. Navy auxiliaries have been intentionally designed and utilized to perform only supporting tasks which fall well within current legal norms. These include providing logistical support, or serving as air or seaborne launch pads to transport troops and ammunition. But there is an increasing desire to expand the functions which auxiliaries can execute, including electronic attack, intelligence collection, command and control, and mine countermeasures. To the extent these and other missions could be construed as belligerent acts, the current rule straitjackets auxiliaries in armed conflict. As the potential list of activities performed by auxiliaries expands, the legal restriction against belligerent acts by auxiliaries has imposed an unnecessary hurdle in operational planning and execution.

The presence of civilians aboard many naval auxiliaries should not impose a limitation on belligerent actions based on ship type. Recognizing that noncombatant civilians may not directly participate in belligerent acts, the possibility for the vessel to exercise combatant functions remains undiminished so long as there are personnel aboard who may lawfully carry them out. The domestic legal hurdles in activating or deputizing civilians to serve in a combatant capacity does not eviscerate the underlying principle authorizing naval auxiliaries to conduct belligerent acts. An auxiliary ship manned exclusively by uniformed military personnel (as is the norm for many countries such as Japan) certainly should raise no concerns warranting imposition of any legal limitations about whether it commits belligerent acts or not. Accordingly, even if there may be legal restrictions on who commits such acts, there should be none based on the class of ship or the functions it performs.

Origins of the Prohibition

The current prohibition against belligerent acts by auxiliaries may originate in large part as a legacy of pre-World War I conventions seeking to protect civilian merchant ships from unnecessary harm. Consistent with notions of fairness among the advanced powers at the time, the 1909 London Declaration Concerning the Laws of Naval War imposed a requirement on warships to distinguish between the enemy’s warships and their merchant ships. If a warship encountered an enemy merchant ship, they were generally not authorized to immediately attack and destroy it even if they had war-sustaining equipment and supplies aboard. Instead, warships were required to first search the merchant ship and take it to a prize court if contraband was found. They could destroy it only in exigent circumstances after safeguarding its crew.The presumption was that even public vessels (but not warships) under the orders of an enemy government were manned by noncombatant civilians unable to inflict harm to any warship. This guidance was reaffirmed by the 1936 London Treaty, and the U.S. considers these procedures legally valid even today. In exchange for these protections, merchant ships were reasonably prohibited from engaging in belligerent acts, but could act in self-defense.2

Yet there was strong recognition that at some point, any vessel controlled by a belligerent government should be treated akin to a warship. During the negotiation of the 1907 Hague Convention Relating to the Conversion of Merchant Ships into Warships, the British delegation suggested the establishment of a special category of warships called ‘auxiliary vessels’ covering neutral or enemy merchant ships which directly aid the enemy’s military forces.3 Although the proposal was subsequently withdrawn, the parties did create a construct allowing the targeting of enemy merchant ships converted into warships. Notably, the conversion process did not require any physical alterations to the merchant vessel which would give it the ability to fight with traditional warships; it only required the ship to be commanded by individuals commissioned by their government, subject to military discipline, and under government control – administrative changes allowing both the ship and its crew to lawfully fight as combatants.4 Even though it did not directly authorize auxiliaries to conduct belligerent acts, the convention established a path allowing merchant ships and other support vessels to do so.

Disconnect Between Targeting and Conduct

Problems implementing the conversion process in World War I led to a relaxation of the targeting rules against belligerent merchant ships while keeping in place the restrictions against belligerent acts. States such as the U.S. continued to demand an evaluation of armament to determine if a merchant ship was actually a targetable warship. But after this evaluation process exposed German submarines to harm, all merchant ships became eligible targets, and the protections bestowed by pre-war conventions were rendered useless. Any ship conducting war-sustaining activities was targeted and sunk by belligerents during the war, regardless of whether it was legally characterized as a warship or not. Yet even armed merchant ships ordered by a belligerent government to attack enemy submarines (i.e. ships that had arguably been converted into warships) did so at considerable legal risk. One British merchant ship captain trying to ram a German submarine was subsequently executed by the Germans as an illegal combatant.5 Because he acted prior to the issuance by the British Admiralty ordering all British-flagged merchant ship masters to take such offensive measures, it is unclear whether the German court would have found him guilty subsequent to the Admiralty’s orders.

The Shipping Act of 1916 strengthened the U.S. military’s authority to directly control the U.S.-flagged merchant marine fleet in wartime. The law authorized placement of its merchant marine under direct U.S. government control for use as an auxiliary force in support of military wartime needs. The law made a clear distinction between the Naval Reserve, which included civilian ships available for requisitioning by the government, and naval auxiliaries, which were ships used by the U.S. government for its military needs in support of the combatant forces, and manned by a crew subject to its direction. When the law was invoked after the U.S. entered the war in 1917, some vessels reported to a civilian Shipping Board, and others came under direct Navy or War Department control. In practice, ships under military control were armed only for defensive purposes, and unlike their British counterparts were never directed to attack the enemy. Nonetheless, for purposes of the 1907 Hague Convention, they were arguably converted into warships because the government had direct control over the actions of a crew subject to military discipline. Otherwise, they were essentially auxiliaries which lost the targeting protections afforded under the 1909 London Declaration without an accompanying legal right to engage in belligerent acts.

World War II strengthened in practice the legal right of armed merchant ships to engage in belligerent acts because they were so closely integrated with the combatant fleets. Both sides treated them in the same manner as warships, both in terms of targeting them, as well as in the scope of belligerent activity they performed. The Allies struggled to prosecute German Grand Admiral Karl Doenitz for violating a provision of the London Naval Treaty of 1930 affirming the requirement to avoid destroying merchant ships unless necessary, and only after safeguarding the lives of merchant ship crews prior to destruction. Doenitz was ultimately acquitted of the charge in large part because the Allies also practiced unrestricted submarine warfare, targeting enemy merchant ships and merchant mariners because they were deemed combatants integrated with fighting forces.6

Establishing a New Rule

Even as World War II saw the de facto incorporation of each side’s merchant marine into their armed forces, the U.S. continues to restrict auxiliaries from committing belligerent acts based on its interpretations of the law of naval warfare, while also recognizing them as lawful targets in international armed conflict. It carefully scrutinizes the intended mission of each ship to determine if it needs to be ready to commit belligerent acts. If it does, it is commissioned as a warship (i.e. with a “USS” designation) rather than brought into service as an auxiliary (i.e. with a “USNS” designation). Any changes in mission may require adjustments in the ship’s status. Although seemingly just a paper drill, the reality is that it significantly impacts manning, maintenance, planning, and operations, and reduces the flexibility of the operational commander in executing desired missions.

There should be no prohibition against auxiliaries committing belligerent acts. They are fully integrated into naval forces for the sole purpose of prosecuting the conflict onto the enemy, and as such are lawful targets. Indeed, the enemy will evaluate the ship’s targetability based on the platform rather than the personnel aboard, whether military or civilian. Potential law of war restrictions on embarked civilian personnel to exercise combatant functions are only administrative impediments that can be adjusted consistent with domestic law procedures, and should have no bearing on whether the execution of belligerent acts should be limited based on ship type. When subject to the direction of the armed forces on non-commercial service, naval auxiliaries are not innocent merchant ships posing no threat. These vessels execute a vital military mission and as such are lawful targets as much as any traditional warship. To the extent naval auxiliaries have the capacity to commit belligerent acts, it should be lawful for them to do so.

Commander David Lee is a military professor at the Stockton Center for the Study of International Law, located at the U.S. Naval War College in Newport, RI. He most recently spent five years practicing international and operational law in support of U.S. Naval Forces Europe/Africa and U.S. SIXTH Fleet in Naples, Italy.


1. 1909 Declaration Concerning the Laws of Naval War, Chapter IV.

2. 1913 Manual of the Laws of Naval War, Article 12.

3. Proceedings of the Hague Peace Conferences, Vol. I, Oxford University Press (New York: 1920), 235.

4. 1907 Hague Convention Relating to the Conversion of Merchant Ships into Warships, Articles 2-7.

5. Charles Dana Gibson, Merchantman? Or Ship of War, Ensign Press (Camden, ME:  1986) 46.

6. Id., 119-121.

Featured Image: USNS Carson City (T-EPF- 7) entering the Black Sea on Aug. 15, 2018. Photo by Yörük Işık, @YorukIsik.

Call for Articles: Integrated Naval Force Structure Topic Week

By Dmitry Filipoff

Submissions Due: November 4, 2019
Week Dates: November 11-15, 2019
Article Length: 1000-3500 words
Submit to: Content@cimsec.org

The U.S. Navy and Marine Corps are initiating an Integrated Force Structure Assessment to help chart the course of their future composition.

This force structure assessment process is unique in its emphasis on unmanned platforms by considering “an optimal force mix that includes Large Unmanned Surface Vessels, Extra Large Unmanned Undersea Vessels, and Expeditionary Advance Bases.” 

It may also look to overhaul the Marine Corps’ force structure, where in reference to its longstanding use of large, expensive platforms the new Marine Commandant Gen. Berger wrote in his planning guidance that they must “seek the affordable and plentiful at the expense of the exquisite and few when conceiving of the future amphibious portion of the fleet.”

The assessment hopes to nest future force structure within emerging warfighting concepts such as Distributed Maritime Operations (DMO), Littoral Operations in a Contested Environment (LOCE), and Expeditionary Advanced Base Operations (EABO). (Click below to read the memo from the Navy’s Chief of Naval Operations and the Marine Commandant.)

What ships and platforms will best serve the national security interests of the nation, capture technological opportunities for advantageous capabilities, and meet the challenge of great power competition? Authors are invited to answer these questions and more. Please send all submissions to Content@cimsec.org

Dmitry Filipoff is CIMSEC’s Director of Online Content. Contact him at Content@cimsec.org

Featured Image: PACIFIC OCEAN (Jan. 20, 2018) Amphibious assault ship USS America (LHA 6), front, transits the Pacific Ocean next to Nimitz-class aircraft carrier USS Carl Vinson (CVN 70). (U.S. Navy Photo by Mass Communication Specialist 2nd Class Sean M. Castellano/Released) 180120-N-BL637-0045

Notes to the New CNO Week Concludes on CIMSEC

By Dmitry Filipoff

Last week CIMSEC featured articles submitted in response to our Call for Articles requesting short submissions where contributors offered their suggestions to the U.S. Navy’s new Chief of Naval Operations, Admiral Michael Gilday. From future warfighting considerations to the management of the force, authors provided a variety of hard-hitting insights.

Below are the articles and authors that featured during the topic week. We thank the authors for their excellent contributions. 

Two Unaddressed Problems in the Surface Navy” by Matthew Harper, CDR, USN (ret.) 

“A lot has been written about the troubles of the U.S. Navy’s surface force, but two underlying institutional problems have not been fully addressed. The failure to address these flaws promises that the U.S. Navy’s surface force will continue to risk generating less capable Sailors who are more risk averse and less tactically astute.”

Prepare for Autonomous Undersea Conflict” by David Strachan

“Undersea warfare is entering an era of profound transformation due to the increasing sophistication and proliferation of unmanned systems. But while their roles, missions, and concepts of operation have been thoroughly analyzed, the ultimate deployment of autonomous, expendable vehicles in a shadowy, hostile environment could unfold in ways that have yet to be fully imagined.”

Make Crew Endurance an Operational Warfighting Imperative” by Captain John Cordle, USN (ret.)

“The Navy owes Sailors a culture that maintains its people with the same rigorous mindset and planning as the maintenance of its ships and aircraft. Proper crew rest and sleep hygiene not only improve the daily performance and long-term endurance of our personnel in stressful environments, but best practices will lead to better long-term health outcomes when our Sailors leave the service.”

Reestablish the Strategic Studies Group” by Commander Chris O’Connor, USN, and Lieutenant Commander Ryan Hilger, USN

“The SSG’s original mandate, to develop and propose innovative warfighting concepts against peer competitors (initially the Soviet Union), is quite relevant today. The new CNO should reestablish the SSG along these lines to develop a new generation of strategists and operational concepts for Navy and Marine Corps warfighting.”

Recapitalize Sealift or Forfeit the Next Great Power War” by Stephen M. Carmel

“In the U.S., at least in terms of sealift, incrementalism is our watchword and even then we don’t execute on that minimal vision. The focus is always on doubling down on failed programs and policies that brought about the current state of affairs when bold, innovative thinking that does not repeat the mistakes of the past is required.”

Every Sailor a Cyber Warrior” by Lieutenant Douglas Kettler, USN

“The next level of fleet-wide cyber education should show the Sailor how the domain impacts their lethality and arms them with the education to recognize, respond, and overcome adverse cyber effects. Through the new creed of ‘every Sailor a cyber warrior,’ the CNO will be able to leverage his experience at Tenth Fleet to arm the Navy with the foundational skills necessary to fight and prevail in twenty-first century network-centric warfare.”

Defend and Advance Core Undersea and Network Capabilities” by John T. Kuehn, Ph.D., Commander, USN (ret.)

“The Navy must emphasize fielding proven technology. Do not bank on emergent technology that only currently exists on paper and in formulas, and is not something that can be fully operationalized into the fleet we have by 2030.”

To Win Great Power War, Treat Information As a Strategic Resource” by Lieutenant Commander Robert “Jake” Bebber, USN

“The Navy and Joint Force should be part of a national strategy that harvests information resources and controls critical information industries while denying that leverage to our adversaries. This requires new operational concepts, deeper relations with partners, allies, and industry, and a re-thinking of current personnel recruitment, training and retention.”

Restore Authority and Accountability” by Commander Rob Brodie, USN

“The cause of the Fitzgerald and McCain collisions was the administrative chain of command’s decisions to send untrained officers to the fleet while also replacing intuitive with non-intuitive ship control consoles without training support. But instead, only the operational chain of command was held accountable for the loss of life.”

Tackle Force Dynamism and Administrative Structure For a Stronger Navy” by Petty Officer Second Class Jacob Wiencek, USN

“The CNO should focus on his role of training, developing, and administratively overseeing the U.S Navy, specifically in two key areas that are adversely affecting the fleet: administrative and personnel structure, and force dynamism.”

The Navy Reserve is Broken” by Lieutenant Blake Herzinger, USN

“Navy reservists are ready and eager to serve, but what message do they receive when they arrive on deployment and are told the duties they have arrived to execute are unimportant or nonexistent? Administrative problems have administrative solutions, but without attention from above, they will languish and Sailors will suffer the consequences.”

Junior Personnel: The X-Factor in Great Power Competition” by Lieutenant Adam Johnson, USN, and Lieutenant Junior Grade John Maslin, USN

“Incorporating a non-discriminatory dataset from the junior ranks into senior-level decision-making could be an ‘X-factor’ for several reasons. First, it would provide senior leaders with crowdsourced, deckplate-level data that, in many cases, they are currently not receiving. Harnessing these collective insights from a generation that has grown up in a technology-fueled world that is entirely dissimilar from the early experiences of our senior leaders could pave the way for new strategies for how the Navy conducts business.”

Kill the Darlings and Pet Programs” by Lieutenant Commander Ryan Hilger, USN

“It is time to kill our darlings. We cannot deploy the Navy the nation needs with the many pet programs we have. Underperforming programs must go. Follow Secretary Esper’s lead and hold ‘Night Court’ for the Navy…”

Don’t Forget Seapower’s Dry Foundation” by J. Overton

“Important as that role is, bases’ size, location, and presence means they are continuously carrying out effective naval strategy. Some of that is direct and traditional – overhauling ships, fueling aircraft, training submariners. But much of that is better described as ‘collateral strategy’ – using the means available through local presence to establish global ends. “

Improve Mutual Cooperation with Small and Medium-Sized Navies” by VADM. (Ret) Omar Eduardo Andujar-Zaiter, DRN

“The CNO should include in his working plan a desire to better understand and collaborate with small and medium-sized Navies of nearby democratic countries with the aim of earning bilateral cooperation for USN objectives. For this the CNO may connect through person-to-person visits and calls to the leaders of these navies to earn a better understanding of how other international naval forces operate and contribute to regional security.”

Please Stop Making Sailor-Soldiers” by Lieutenant Zachary George, USN

“It is time again to get the reserves back to sea. The CNO must direct the Chief of the Navy Reserve and the Chief of Naval Personnel to quickly make both the Reserve Surface Force and the greater global force management process a system that mobilizes Sailors into Sailors, and not Sailors into soldiers.”

Dmitry Filipoff is CIMSEC’s Director of Online Content. Contact him at Content@cimsec.org

Featured Image: NORFOLK (Aug. 27, 2019) Chief of Naval Operations (CNO) Adm. Mike Gilday visits with Sailors aboard USS Kearsarge (LHD-3). (U.S. Navy photo by Chief Mass Communication Specialist 2nd Class Nick Brown) 

Fostering the Discussion on Securing the Seas.