Publication of working papers for the SPF project “Shaping the Pragmatic and Effective Strategy Toward China”

 IINA (International Information Network Analysis) will upload the working papers written by U.S. and Japanese project members focusing on shaping a pragmatic and effective strategy toward China. We hope that this series will help IINA readers understand how experts from the U.S. and Japan see China and the U.S.-Japan joint efforts, which have the potential to determine the future world order.

The shifting balance of economic and military power in Asia requires an urgent revision of the roles and missions and the specialization of labor within the U.S.-Japan alliance. Yet there appears to be little interest in either Washington or Tokyo for serious dialogue on these topics. Washington is largely distracted by other issues and appears content to see a relatively greater effort on Japan’s part, while the topic of roles and missions remains suspect in Japanese defense circles, where alliance specialization once meant the subordination of certain, generally defensive, tasks to Japan. When roles and missions within the alliance are mentioned today, it is often to note simply the expansion of Japan’s defense functions[1].

While roles and missions should evolve with strategic circumstances, the simple expansion of Japanese roles and missions—and the construction of a miniature replica of U.S. force structure—is almost certainly not the most advantageous way for the alliance to allocate scarce resources. Building from new or evolving concepts of operation, developed in response to evolving threats, this paper proposes a set of criteria by which roles and missions might be reconsidered. The paper focuses primarily on building capabilities relevant to deterrence vis-à-vis China. Although the paper discusses hypothetical conflict, it should be understood that it is not sought or expected, but that deterrence requires plausible capabilities to prevail in such conflict – topics that are difficult to address without delving into the likely course of such a development.

Under the framework outlined below, roles and missions would not be strictly national in nature, but rather determined by geography and a unified set of concepts of operation. The bulk of Japanese military forces—as well as U.S. forward deployed forces in the Western Pacific—would be structured and postured to operate in a highly distributed manner as part of an inside (or denial) force, designed to prevent domination of the air and sea space by China[2]. Forces outside the theater, including many but not all U.S. military elements, would be more conventionally organized. This would drive national differences and a degree of specialization, but the distinctions would not be absolute.

The first section immediately below outlines the conditions that have made a new approach to roles and missions necessary. The second section outlines the principles on which a new conception of roles and missions might be based. The third section sketches out some of the changes that such a division would entail for Japanese and U.S. forces. And the final section addresses questions and potential counterarguments. I argue that while the functions assumed by Japanese forces (as well as forward deployed U.S. forces) would be largely defensive, the operational concepts employed would be highly dynamic and include offensive action. Moreover, Japanese forces, together with select U.S. elements, would represent an elite “inside force,” designed to operate within the highest threat areas.

Before moving on to discuss roles and missions, it is worth noting that other aspects of the alliance are also in need of reevaluation, including the level of Japanese defense spending, the outdated special measures agreement, and specific aspects of the U.S. Marine Corps presence in Okinawa. Among important alliance issues, however, roles and missions has perhaps received the least critical attention[3].

Background: The Shifting Balance of Power and Evolving Technology

Two developments are driving the need for a vigorous discussion of roles and missions within the alliance. One is the shifting balance of regional power and the likely correlation of forces at the outset of a potential conflict. The other is a broader, technological development involving the impact of long-range precision fires.

Shifting balance of power. The shifting balance of power requires little elaboration. As late as 2005, Japan’s gross domestic product (GDP) was more than twice that of China’s; in 2021, China’s was more than three times that of Japan. The asymmetry in defense spending is even greater, and the imbalance of resources is steadily generating an equally large imbalance in capabilities.

The connection between the balance of power, geography, and alliance roles and missions is less often noted. Japan assumed primarily defensive tasks within the alliance during the early Cold War period not only because of its limited military capabilities and constitutional concerns with building more, but also because of the adverse balance of power within the immediate theater. The proximity of Hokkaido to Soviet-occupied territory and the naval, air, and ground forces located there made Japan highly vulnerable to a land grab by the Soviet Union. Despite overall U.S. superiority in naval power, U.S. reinforcements would have arrived only slowly, and the allies would have depended heavily on Japanese defensive capability during the early phases.

As allied resources and confidence grew during the late 1970s and 1980s, Japanese roles and missions expanded to include a range of missions that were less exclusively defensive, including, most prominently, the defense of sea lines. During the immediate post-Cold War period, the defense of Japan’s home islands became a distant thought, and the discussion of roles and missions turned to Japan’s role on the broader regional and global stage.

The alliance has, however, entered a far more challenging period, and the problem of deterring attack against Japan is again front and center. To be sure, potential military contingencies are quite different than those of the Cold War. There is little threat that Japan’s main islands will be invaded, though attacks on Japanese bases or outer islands are entirely possible. In the mid- to long-term future, as Chinese capabilities continue to grow and as potential battlegrounds expand to include the area between the first and second island chains, Chinese attempts to seize other small Japanese islands in the Ryukyu chain for tactical advantage in ongoing operations elsewhere are also becoming a more realistic contingency[4].

To be sure, there is little chance that Chinese leaders will simply wake up one day and decide to attack Japan, barring, perhaps, a severe crisis over the Senkaku Islands. Nevertheless, crises elsewhere in the region, particularly Taiwan, could draw the alliance into conflict. Both Tokyo and Washington have important interests in preventing an armed assault across the Taiwan Strait. Were the alliance to become involved in a conflict over Taiwan, China would have incentives to strike U.S. and Japanese bases in Okinawa and, as the conflict progressed, possibly against bases in Kyushu and Honshu as well.

Nor would these be one-off attacks. The entire area would likely see high-intensity air and naval operations, with the People’s Liberation Army (PLA) seeking to suppress U.S. and Japanese military forces and prevent them from coming to the aid of Taiwan. Needless to say, U.S. and Japanese forces would return fire and look to sink any Chinese ships involved in invasion or blockade operations and, perhaps, attack Chinese airbases and missile sites along the Chinese coast.

While the specific manifestation of conflict would be quite different than that anticipated during the Cold War, the correlation of forces is coming to resemble more closely the 1960s and 1970s than the 1980s or 1990s[5]. Again, although the United States maintains large reserves of high-quality forces, the large preponderance of them are not located in the Western Pacific, and they would take time to arrive in the immediate theater. Hence, the Japan Self-Defense Forces (SDF), together with forward deployed U.S. elements, would be tasked with fighting a delaying action while U.S. reinforcements, and hopefully those of other allies and partners, mobilize.

Evolving technology. The second important factor driving the need to reconsider roles and missions is the evolution of military technology. The long-range precision strike has radically altered air and naval warfare. Much like the rifle and machine gun changed ground warfare during the 19th and early 20th centuries, missiles have dramatically increased lethality and range in our own time.

Ships and airbases can be struck by assets located in a far wider geographic arc than was once the case. Concentrated soft targets, such as aircraft on airbases, are particularly vulnerable, as missiles armed with submunitions (i.e., cluster weapons) can spread explosives over a wide area. The ability to network missiles and retarget them in flight makes concentrations of ships at sea vulnerable to attacks by anti-ship missiles. Active defenses against missile attacks do exist and can complicate the task of an attacker, but the missile defense “umbrella” is leaky at best, highly expensive, and can be overwhelmed by salvos of attacking missiles.

In the face of more lethal infantry and artillery weapons in the 20th century, armies dispersed formations, increased mobility, and bypassed strongpoints in the attack to mitigate casualties[6]. Today, naval and air planners are experimenting with and adopting new methods to counteract the threat posed by accurate, long-range missiles. While there is no single answer, a central concept is distributed operations. Naval and air forces would disperse, with assets physically separated from one another over wide areas, but nevertheless able to exploit the potential of networked systems to concentrate fires. Enhanced mobility, together with camouflage and concealment, would supplement dispersion, and fixed infrastructure would be hardened.

These new concepts have been built into evolving U.S. and Japanese military doctrine. In the U.S. case, the Joint Concept for Access and Maneuver in the Global Commons (JAM-GC) provides guidance at the joint level. The Air Force has adopted a concept called Agile Combat Employment (ACE); the Navy Distributed Maritime Operations (DMO); the Marine Corps Expeditionary Advanced Base Operations (EABO); and the Army Multi-Domain Task Forces (MDTF). In the Japanese case, decisions to maintain a larger submarine and supplement large destroyers with new classes of smaller warships is broadly consistent with an emerging notion that denial, rather than absolute sea and air control, is becoming more important.

When considered from first principles, however, the implications go further than service or joint doctrine for each of the allies individually. New technology, the shifting correlation of forces, and geography also produce effects around which a new military division of labor (or definition of roles and missions) should be built.

New Organizing Principles for Roles and Missions

The developments discussed above have two further effects that are critical to understanding how the U.S. and Japan can best organize their military forces and operating practices: phases of conflict; and the layering of forces (or the distinction between the so-called “inside” and “outside” forces, discussed further below). These effects are each shaped by somewhat different driving forces, but both nevertheless suggest similar things about the organization of forces and the characteristics that will be most in-demand.

Phases of conflict. Conflicts can unfold in any number of ways, with initial stages differing significantly from intermediate and later stages. In the most plausible East Asia contingencies, including those in which the U.S.-Japan alliance might find itself engaged, the correlation of in-theater forces, together with geography and the larger balance of power, will define likely patterns.

The U.S., with a defense budget close to $800 billion and equipment and expertise that has been assembled over a period of decades, continues to enjoy significant advantages over the Chinese military. To be sure, geography and asymmetric approaches by the PLA go far in leveling the playing field and mitigating U.S. strengths, but given time to mobilize and deploy, U.S. advantages would likely inexorably push China onto the defensive — assuming it is not able to achieve its objectives quickly or cripple U.S. and Japanese forces in ways that fundamentally undermine political resolve. Needless to say, the emphasis on U.S. reserves of military forces would not alone be decisive; Japan and, potentially, other allies also contribute powerfully to aggregate superiority.

Regardless of aggregate allied superiority, however, the initial phases of conflict would likely be characterized by a poor correlation of forces. Only a fraction (roughly 10-15%) of U.S. naval and air power is located in the Western Pacific, with other INDOPACOM assets in Hawaii and the U.S. West coast (and the possibility of reinforcing those further with forces coming from other major commands). During the early phases of conflict, therefore, the alliance would be very much on the defensive, regardless of whether Chinese goals were in Taiwan, the East China Sea, or (possibly) the South China Sea. Chinese missile inventories would be intact, and its space, communications, and command and control would be similarly whole.

During the initial stages of conflict, the alliance would have three primary goals. The first would be preventing fait accompli, particularly in the case of an assault on Taiwan. The occupation of smaller, unpopulated islands could be reversed relatively easily once air and sea control is established, but if China were to occupy Taiwan, the task of retaking it against a PLA force that had consolidated gains and dug in would be an extraordinarily difficult military task, even if the political will were present. The second goal would be avoiding debilitating losses to military forces or infrastructure that could either undermine political will in Washington or Tokyo or make reinforcement a substantially more difficult proposition. The overall costs of conflict (and aggregate military losses) would be far higher if U.S. reinforcements were entering a region already dominated by China, rather than falling in on and reinforcing an intact and functioning defense. And the third goal would be attriting adversary forces to prepare for counteroffensive action designed to bring about war termination.

The course of subsequent phases of conflict would vary depending on circumstances, but goals would include the defeat of Chinese forces engaged in offensive action, the recovery of any territory or positions lost during initial phases, and the termination of conflict on satisfactory grounds. Escalation risks would likely be carefully considered at every step, but a variety of offensive measures might be envisioned, including (1) degrading Chinese space-based and other ISR capabilities; (2) strikes on Chinese bases supporting offensive action (e.g., forward airbases hosting large numbers of Chinese combat aircraft or military port facilities engaged in reloading naval munitions or landing forces); (3) blockades, either conducted at a distance or, potentially, through the mining of Chinese harbors; and (4) amphibious operations designed to retake lost territory.

There would be no clear demarcation between phases, and both defensive and offensive activities would be conducted throughout, with the balance changing over time. Some of the offensive activities described above would, however, require a series of preparatory measures and conditions. Crossing water, even to reinforce one’s own positions, will be extraordinarily hazardous in the face of active missile threats and intact ISR.

Distributed operations and the “inside” and “outside” force. A second implication of recent trends, particularly the evolving nature of military systems and warfare, is the nature of dispersion across the battle space in distributed operations. Both the U.S. and Japanese militaries are looking to capitalize on the ability of modern naval and air forces to operate in a dispersed manner, thereby reducing vulnerability, while still being able to concentrate fires. Achieving mass, marshaling superior force at the decisive point, has always been a maxim of warfare, and distributed capabilities provide the means to achieve “virtual mass” without some of the modern risk associated with physical mass.

Distributed forces may be dispersed in breadth (along the front) and depth (away from the front). Dispersion across the front is self-explanatory, but inherent in dispersion in depth is the positioning of different kinds of military forces and assets at different distances from the primary battle area (or threat). There are various ways of describing the forces that might be deployed relatively far forward or farther to the rear. The simplest descriptor is simply geographic. JAM-GC, for example, distinguishes between the “inside force,” which would include assets well equipped to operate close to or within the adversary’s primary threat rings (e.g., within range of enemy missiles), and the “outside force,” which would operate beyond those areas[7].

Other U.S. documents employ more complex, functional descriptions. The 2018 NDS, for example, describes four “layers[8].” Forces in the Contact layer can be within visual sight of the adversary and combat gray zone operations. Forces in the Blunt layer are intended to deter, delay, degrade, and deny full control of (or fait accompli in) forward areas against attack. Forces in the Surge layer would flow (or surge) into theater to defeat aggression and terminate conflict on preferable terms. And the forces in the homeland defense layer would continue to deter attacks against the U.S. itself.

For the remainder of this document, I will simply refer to the inside force (which corresponds roughly to the blunt layer forces) and the outside force (which corresponds roughly to the surge layer forces), and I will use those terms in reference to the alliance as a whole, rather than just U.S. forces.

The inside force — deployed relatively close to the adversary and charged with delaying and degrading the adversary and denying him full control to the adversary — would include assets with a number of characteristics. These would be forces that are (1) more survivable, whether because of mobility, hardening or the ability to hide; (2) armed with shorter range weapons; (3) capable of providing intelligence and reconnaissance to the outside force; and (4) more attritable (e.g., smaller, cheaper, and less catastrophic if some portion is lost). The ongoing conflict in Ukraine has validated the notion that dispersed forces, equipped with precision strike and adequate ISR, can contest attack by larger and more heavily equipped forces.

Characteristics of the outside force are generally the opposite and include large systems that may be difficult to hide or protect, are equipped with long-range capabilities, and the loss of even a few of which would be expensive and painful.

Adjustments to Force Structure and Posture

The considerations outlined above, and their relation to geographic position, phases of conflict, and the function of different kinds of forces, suggest a natural division of roles and missions. This would not be strictly national, but would, rather, be based largely on the location of peacetime deployment. Forces within the immediate theater, whether Japanese or American, would be optimized and weighted for the inside fight, while reinforcements likely to arrive significantly after the opening of hostilities would be optimized and weighted to play the role of the outside force.

This distinction need not and should not be absolute. The inside and outside forces serve different functions, and both will be required from the outset for a distributed defense to function properly. Some portion of U.S. and Japanese forces based in Japan can redeploy quickly to areas farther from high-threat areas and assume the role of the outside force, while a portion of U.S. forces flowing into the region from outside the immediate theater can move to reinforce the inside force. Moreover, some services or categories of forces are more suited to play one role or the other.

Nevertheless, the paucity of forces available in theater at the outset of conflict means that a large proportion of forward deployed forces — whether Japanese or U.S. — should be conceived of as the inside force and designed to deny the adversary full control over areas around the first island chain while providing ISR to heavier forces farther away. And although the distinction would not be strictly national, Japan, as the partner providing the bulk of the forces in-theater at the outset of conflict, would optimize the bulk of its military for the inside fight.

A number of adjustments to force structure and posture follow from these observations and produce a division of military labor between Japan and the United States, albeit one that is softer than the division seen during the early Cold War period. The comments below focus primarily on adjustments to the Japanese force structure, but also address adjustments to the U.S. military. It should be noted that some changes consistent with these suggestions are being made, but that a variety of factors, in some cases internal to the military and in others external, have impeded their speed and scope.

Service balance. The relevant contingencies in Northeast Asia’s archipelagic environment would be overwhelming air and maritime contests. Taiwan, with a landmass of about 14,000 square kilometers, is an exception, but the defending ground forces would be almost entirely Taiwanese. Although Japanese and U.S. ground forces would play a role in these contingencies — in part by providing anti-air and anti-ship capabilities as well as securing key sites — command of air and maritime areas would largely decide these contests. Ground forces cannot cross water in the face of modern missiles unless at least local air and maritime superiority is achieved, and until more complete air superiority is achieved such operations would be highly risky, even with local advantage. Relevant ground forces, for their part, would be small, but equipped with sophisticated systems.

The Pacific War’s Guadalcanal Campaign (or the larger Solomons Island Campaign, of which Guadalcanal was a part) is instructive of the types of battles that might be fought in this archipelagic geography. Ground actions were important for securing airbases, but the scale of ground elements seldom exceeded a few thousand individuals on each side, whereas any number of large scale naval and air battles were fought, including two of the war’s five carrier battles, a number of large surface actions, and an extended air campaign engaging hundreds of aircraft on each side.

Budgets for the SDF, which continue to heavily favor the Ground Self-Defense Force (GSDF), are a legacy of an era that is long past, one in which the SDF was largely charged with the ground defense of Hokkaido while the U.S. supplied the bulk of the air and naval capabilities. The GSDF force structure has been reduced in size and, to its credit, recast for relatively rapid transport and given additional anti-air and anti-ship assets.

Nevertheless, the fact that the GSDF’s budget is larger than that of the other services is one of the more dysfunctional elements of Japanese defense. It produces underinvestment in the Air Self-Defense Force (ASDF) and Maritime Self-Defense Force (MSDF) and suboptimal compromises with respect to air and maritime capabilities. Rather than simply enhancing the anti-air and anti-ship functions of the GSDF, the MSDF and the ASDF should be given larger roles in defining military strategy and setting the agenda with respect to archipelagic defense. Any assessment of Japan’s defense capabilities should begin with a shift in resources from the GSDF to the other services, as well as larger overall defense budgets.

U.S. military budgets are also likely to be more constrained in the immediate future as Washington confronts the public debt, infrastructure requirements, the economic effects of the COVID pandemic, and a public that has tired of military commitments. Even if budgets are not reduced outright, they will nevertheless probably not keep pace with inflation. Under those conditions, too, difficult choices must be made. More will be expected of allies that spend below their potential, including European allies and Japan. Under these circumstances, it stands to reason that the U.S. should also reduce the size of its ground forces, particularly those of the Army, while strengthening air and maritime capabilities.

Naval forces. The U.S. and, particularly, Japan should introduce a range of smaller, more attritable naval elements for the inside battle. These will include unmanned surface vehicles and frigates that are smaller, cheaper, and stealthier than the Aegis destroyers and cruisers that have been the mainstay of both fleets[9]. These ships can conduct a variety of missions in high-threat areas, including escorting small carriers and transport forces, anti-submarine warfare, and, to some extent, air and missile defense. While there will still be a need for some larger surface combatants, it stands to reason that the proportion of destroyers will decline significantly as the number of smaller ships increases. Given that the cost of a Mogami-class frigate is one-third that of an Atago-class destroyer, Japan should be able to increase significantly the number of surface combat units in the water.

However, even as the MSDF downsizes the average size of its surface combatants, it should complete the conversion of its four Hyuga and Izumo-class ships into aircraft carriers and replace the Hyuga-class ships with larger (30,000 to 40,000-ton) carriers as the Hyuga ships are retired. While all assets, including carriers, will be at risk in any future conflict, these light carriers will be useful in providing air power that can supplement ground-based air forces, which operate from fixed locations that are likely to come attack early in a conflict. The carriers’ mobility, combined with their ability to operate from beyond the island chain, will provide them a degree of protection.

The U.S. Navy should also accelerate the construction of elements suitable for the inside, denial battle, though it will also want to maintain a portion of its fleet for more traditional operations. It should forego designing a follow-on cruiser to the Ticonderoga-class and Zumwalt-class, continue construction of the Burke Flight III ships, and shift the resources that might have been allocated to cruisers towards the construction of a substantial frigate and USV fleet. Given the difficulties the navy has had in developing innovative frigates — the Constellation-class is an unexciting and tradition-bound replacement for the unsatisfactory Littoral Combat Ships — it might consider procuring the Japanese Mogami-class.

The U.S. Navy should also reconsider its carrier forces and invest in small, 40,000-ton carriers based on a modified version of the America-class Amphibious Assault Ship. It could maintain six of its traditional large carriers, ships that would be useful in the latter stages of an Asian conflict as well as in contingencies elsewhere in the world, while replacing the remaining five to six carriers with smaller carriers at a ratio of roughly two-to-one. While these would still be large ships, they are more likely to be employed in relatively high-threat environments than would traditional carriers, the loss of which might be regarded as so politically painful that they might be held back far from the action.

Air Forces. Airpower will also be critical to the inside force, and it provides the primary offensive “sting” embedded in such a force. The range and speed inherent in modern aircraft, combined with their ability to launch missiles and rearm quickly, gives them the ability to concentrate fires against adversary fleets and airfields (or at least those airfields nearest the battle areas) and overwhelm defenses. While important, however, airpower can no longer consider its main bases secure, and both the Japanese and U.S. air forces should strengthen active and passive defenses, make substantially increased use of civilian facilities, and adopt a range of new operating practices. The necessary changes, therefore, will be profound, and they will require greater relative spending on sustainment and hardening and somewhat less (again, relatively) on procurement.

Both the U.S. Air Force (USAF) and ASDF should invest in additional passive defense measures. Accurate missiles armed with submunitions and employed against soft targets, including aircraft parked in the open, are area effects weapons. If aircraft remain unprotected, a single missile can destroy multiple aircraft[10]. The construction of hardened aircraft shelters (HASs) can greatly reduce losses. HASs can be destroyed, but only by a direct hit with a unitary warhead, transforming the problem significantly for an attacker and forcing him to employ more than one missile against each suspected aircraft position. Shelters cost money, but for roughly $6-8 million each, shelters can greatly reduce the vulnerability of $100 million aircraft[11]. If redundant shelters are constructed, the adversary may fire a portion of his missiles at empty positions. Camouflage, concealment, and deception (CCD) could have similar effects.

Greater use of civilian facilities will allow Japanese and U.S. air forces to disperse across a greater number of airfields, reduce the density of aircraft on any single field, and improve the effects of CCD. In the event China chooses to close airbases by cutting runways, the employment of additional dual-use or civilian airfields will increase the number of required targets, run down adversary missile inventories, and increase the probability that some runways (and aircraft) remain functional. Most airports in Okinawa Prefecture are small, but they could host F-35Bs, V-22s, and helicopters. Employing major airports on Kyushu would also enable the alliance to base larger numbers of aircraft near conflict areas without increasing vulnerability by massing on the handful of local ASDF bases.

Finally, active defenses (air and missile defense batteries) introduce an additional layer of uncertainty for adversary planners. While the cost-exchange ratio of an interceptor against an attacking missile is poor, the ratio is greatly improved when the adversary faces uncertainty and either allocates too many or too few missiles to individual attacks. Moreover, cost effectiveness should not be judged purely in terms of the cost of defending an asset; by that accounting, one would never invest in body armor for soldiers, since bullets will be cheaper. The point is to defend one’s own systems, so that they can be employed in their operational role, which, in the case of aircraft can involve attacking fleets, adversary bases, aircraft in the air, or submarines.

Japan’s aircraft procurement strategy is generally on the right track to produce the weapons necessary to execute as the inside force. The ASDF should follow-through with procurement of JASSM-ER (ground attack) and LRASM (anti-ship) missiles, make the modifications to the F-15 fleet to enable their launch, and procure JSM missiles for the F-35[12]. The ASDF might consider shifting some of its F-35A procurement to F-35Bs, which will be useful not only on Japan’s light aircraft carriers, but may also be used from small airstrips in the Ryukyu chain. The ASDF should also continue investing more in tankers, which it currently operates in very small numbers. Tankers will give the ASDF greater range and, in the defensive context, greater on-station loiter time. Its current plans for airborne early warning aircraft, anti-submarine aircraft (operated by the MSDF), and cargo aircraft are already adequate (and arguably excessive regarding the last of these).

The USAF has embraced the ACE concept, but it too faces enormous adjustments if it wants to be able to execute agile operations. It is confronting how to reorganize its maintenance wings and squadrons[13]. And it will need to coordinate with Tokyo on all of the same infrastructure issues (e.g., hardening and the use of civilian facilities) discussed above. Perhaps even more than the ASDF, the USAF also confronts questions about how to refresh its antiquated inventory of aircraft and consider how many F-35s it can afford to operate. Air Force Chief of Staff General Charles Q. Brown favors speeding the retirement of older aircraft and limiting the scale of F-35 procurement[14]. These adjustments would produce a smaller inventory in the short term, but dramatically reduce the age of the air fleet and save resources for the more rapid introduction of the Next Generation Air Defense fighter[15].

Ground forces. The GSDF has done much to adjust to the threat, but it continues to maintain large maneuver formations. Those formations and the GSDF’s privileged budgetary position continue to consume resources that might be used to strengthen air and maritime capabilities. In addition to reallocating budget shares among the services, there are ways for the GSDF to contribute more directly to the air and maritime fight.

A number of divisions have been converted into brigades, and much of the force has been made more mobile. The GSDF has increased the number of units that can conduct assaults across bodies of water, including an amphibious brigade (established in 2018) and airmobile brigade (established in 2001) in addition to the previously existing airborne brigade. A number of regiments within other division- and brigade-sized formations have been converted into “rapid deployment regiments,” equipped with small, wheeled armored vehicles in place of larger armored personnel carriers and main battle tanks.

The GSDF’s adjustments are, however, overwhelmingly oriented toward deploying to defend islands against amphibious assault or retaking islands that may have been occupied by adversary forces — in other words, relatively traditional tasks for large maneuver formations[16]. These tasks, and counterattack in particular, require significant investments not just from the GSDF, but also from the MSDF for support. Moreover, they are arguably of secondary importance. Without maritime and, especially, air control of surrounding areas, amphibious assaults by either side are unlikely to succeed. Retaking lost islands would likely wait until the last stages of a conflict, after matters had been substantially settled at sea and in the air.

To fight the inside battle, the GSDF should maintain some rapidly deployable infantry forces to defend important positions, while reorganizing a substantial portion of its force into task-organized units built around anti-ship and, especially, anti-air missile batteries. Anti-aircraft systems, like the Type-03 Chu-SAM, can be employed against cruise missiles, and large numbers of such SAMs could greatly complicate the tasks of the attacker. To be most effective in that role, such batteries (and the task forces in which they are embedded) should be made more easily deployable than existing systems. Hence, smaller, more economical systems should be developed for easy deployment by, for example, C-130[17].

Within the U.S. military, the Marine Corps plans for “greater integration with the Navy.” It has divested itself of all of its M-1 main battle tanks and intends to reorganize many of its existing units into Marine Littoral Regiments (MLRs), capable of conducting EABOs and equipped with systems relevant to air, maritime, and information operations[18]. The Army, for its part, intends to form five Multi-Domain Task Forces (MDTFs), with the first established at Joint Base Lewis-McCord, Washington[19]. The Marine Corps, in particular, has embraced its role as the “inside force,” and, with its historical ties to the Navy, means of delivery, and its own fixed wing fighter aircraft, is in a better position to play a significant role in the air and maritime fight.

In an ideal world, the U.S. and Japan would have redundant and robust capabilities in all domains, but given resource constraints, both are over-invested in ground forces and in greater need of buttressing air and naval capabilities.

Building an Elite, Vanguard Force

The proposed roles and missions outlined above is likely to face interrogation. Is this approach to roles and missions “back to the future” in terms of limiting Japan to defensive roles within the alliance? The answer is a qualified “no.” There are undeniable parallels in the strategic situation faced today and in the early and mid-Cold War period — specifically, a poor correlation of forces in the immediate theater combined with large U.S. reserves located at more distant points. It is then true that an important function of the forces deployed within the theater, whether Japanese or U.S., is to deny an adversary full control of the battle space, a strategically and operationally defensive task.

Yet the distinction between “offensive” and “defensive” is more ambiguous in the air and maritime realms than in the land domain that characterized Japan’s defenses in Hokkaido and other parts of northern Japan during the Cold War, in part because the distinction between operational and tactical warfare is more ambiguous. At the tactical level, the denial approach would include important offensive elements, and these would have effects on the larger course of operations.

It would be more true to characterize the inside force as the elite, light component of the overall force, given both the very high level of operational competence demanded and the tactically offensive capabilities that would be embedded within it. Far from holding static positions, the force would be characterized by enhanced mobility and the ability to attrite an attacker. It would include tactical fighters, lethal, if relatively small warships, and small, highly trained ground forces equipped with advanced communications gear and precision anti-air and anti-ship missiles.

The closest historical analogy to such a force might be the light infantry of the Napoleonic Wars that operated in front of the main body to harass and disrupt the adversary’s main force and to provide early warning and intelligence on it. These forces were not designed to withstand direct, frontal combat against heavy forces, but rather to exploited dispersion, flexibility, and terrain to achieve their objectives. These units, including the famed “Green Jackets” (riflemen) of the British Army, were not subjected to simple mechanical drill but were, rather, expected to exercise initiative and enjoyed status far above their colleagues of the line. A similar, if less institutionalized, parallel in Japanese military history might be the elite, missile (gun) armed Ashigaru units of the late Sengoku period.

If evidence were needed of the mindset sought in the execution of the inside battle, the U.S. Marine Corps, which prides itself on maintaining the most offensive spirit of the U.S. military services, has also been the most proactive service in reorganizing itself to execute distributed operations. It has, in a sense, embraced the inside battle as a position of honor within the larger fight. Similarly, the submarine arm, which would be the first to enter harm’s way and would approach adversary forces more closely than other elements, is characterized by high morale, selective standards, and a sense that they are the Navy’s best. This is not at all, then, a return to the period when Japanese forces were assigned defensive roles in part because of weakness and a lack of mobility, but instead is movement towards a conception in which light, elite U.S. and Japanese forces would operate together on advanced battlefields, while heavier forces operated to the rear.



  1. 1 Jeffrey W. Hornung, “U.S.-Japan: A Pacific Alliance Transformed,” The Diplomat, May 4, 2015; “Priority on Dealing with U.S.-Japan Alliance Perception Gap,” East Asia Forum, April 13, 2021. One paper that addresses roles and missions more seriously is Yoshikazu Watanabe, Masanori Yoshida, and Masayuki Hironaka, The U.S.-Japan Alliance and Roles of the Japan Self-Defense Forces, Sasakawa USA, 2016. This paper agrees with many of the points made in that work, but argues for more thorough changes to make Japanese forces more capable of distributed operations.
  2. 2 The distinction between forces designed for the inside and outside battle are elaborated below. On the denial concept, see Eric Heginbotham and Jacob L. Heim, “Deterring without Dominance: Discouraging Chinese Adventurism under Austerity,” Washington Quarterly, Spring 2015.
  3. 3 The Japanese side raised the issue of military roles at the January 2022 “2+2” meeting, but it appeared to be in the context of expanding the envelope of missions accommodated by Japan, rather than focusing the efforts of each ally on a specific subset of tasks.
  4. 4 Japanese military concern with this possibility is evident in the Japanese doctrinal documents acquired by Konishi Makoto through Japan’s Access to Information law and published in Konishi Makoto [小西誠]、Jieitai no Tousho Senso: Siryoshu (The SDF’s outer island war: collected documents) [自衛隊の島嶼戦争:資料集] (Tokyo: Shakai Hiyosha, 2017).
  5. 5 For metrics related to the evolving balance of power, see Eric Heginbotham et al., The U.S. China Military Scorecard: Forces, Geography, and the Evolving Balance of Power, 1996-2017 (RAND, 2015).
  6. 6 See, for example, Timothy T. Lupfer, The Dynamics of Doctrine: The Changes in German Tactical Doctrine During the First World War (US Army Command and General Staff College, 1981); and Shawn Woodford, “Attrition in Future Land Combat,” Mystics and Statistics (Blog of the Dupuy Institute), June 9, 2017.
  7. 7 For an explanation of this JAM-GC concept, see Expeditionary Advanced Base Operations (EABO) Handbook: Considerations for Force Development and Employment, June 1, 2018, Version 1.1.
  8. 8 Office of the Secretary of Defense, Summary of the 2018 National Defense Strategy of the United States of America: Sharpening the American Military’s Competitive Edge, 2018. See also Mark Gunzinger, Building a Force That Wins: Recommendations for the 2022 National Defense Strategy, Mitchell Institute for Aerospace Studies, 2021.
  9. 9 The MSDF has designed and built a highly successful small frigate that will, to an extent, play this role. On the logic of this purchase, see “ Kaiji no Shingata-goeikan, 4 nenkande 8 seki Kenzo-e(MoD official: MSDF’s new frigate class, eight ships to be built over four years)” [海自の新型護衛艦、4年間で8隻建造へ:防衛省関係者], Reuters, February 17, 2017.
  10. 10 Twenty-five Chinese cruise missiles could cover all potential aircraft parking areas on Kadena Air Base with explosive submunitions. Heginbotham et al., The U.S.-China Military Scorecard, p. 62.
  11. 11 The ROK recently funded the construction of 20 HASs on the U.S. Kunsan Air Base for $125 million, or a little more than $6 million per HAS. “Hardened Aircraft Shelters Constructed at Kunsan,” Kunsan Air Base website, August 4, 2020.
  12. 12 “Japan Retools Plan for F-15 Upgrades by Losing High-Tech Anti-Ship Missiles from U.S.,” Stars and Stripes, August 6, 2021.
  13. 13 Patrick Mills et al., Building Agile Combat Support Competencies to Enable Evolving Adaptive Basing Concepts, RAND Corporation, 2020; Miranda Priebe, Alan J. Vick, Jacob L. Heim, and Meagan L. Smith, Distributed Operations in a Contested Environment: Implications for USAF Force Presentation, RAND Corporation, 2019.
  14. 14 “U.S. Air Force Could Lose Two Squadrons of F-15C/Ds in 2022,” Defense Daily, June 1, 2021.
  15. 15 “Future Fighter Force,” Air Force Magazine, July 22, 2021; Will Roper, “The Air Force’s Secret New Fighter Jet Uses F1-Style Engineering,” Popular Mechanics, January 12, 2021; and “Digital Twins to be New Hallmark for US Air Force Weapons Systems,” Aviation Today, May 3, 2020.
  16. 16 The emphasis is evident in the documents in Konishi Makoto op.cit.
  17. 17 A number of systems that bridge the gap between short-range shoulder fired systems and the Patriot PAC-2 are under consideration in the U.S., including systems that would use either the much smaller AIM-120 AMRAAM missile or the even smaller Peregrine missile. “SAM System That Guards Washington DC Just Made its Lowest Ever Intercept of a Mock Cruise Missile,” The Drive, September 24, 2020.
  18. 18 Force Design 2030, Headquarters Marine Corps, March 2020.
  19. 19 Congressional Research Service, “The Army’s Multi-Domain Task Force (MDTF),” updated April 13, 2021.