Arming Without Aiming? Challenges for Japan’s Amphibious Capability

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Editor’s Note: This is an excerpt from a policy roundtable “The Future of Japanese Security and Defense” from our sister publication, the Texas National Security Review. Be sure to check out the full roundtable.


A centerpiece in Japan’s defense modernization efforts designed to deter a resurgent China is the development of an amphibious warfare capability. The Japanese Self-Defense Force (JSDF) is building up an Amphibious Rapid Deployment Brigade (ARDB). Its primary mission is to “conduct full-fledged amphibious operations for swift landing, recapturing, and securing in the case of illegal occupation of remote islands.” This is a direct reference to China’s growing power projection and assertiveness around Japan’s southwestern Nansei Islands. Deterring China has evolved into a key task for the JSDF and amphibious forces are considered to play an essential role in this strategy. This focus is hardly surprising since Japan is a “frontline” state within the “first island chain” straddling the Western Pacific, and it lies directly within the People’s Liberation Army’s (PLA) inner threat ring of precision strike and other systems.

Japan’s rationale for investing significant resources in an amphibious warfighting capability seems obvious. China poses a major strategic and military challenge to Japan. While the PLA does not yet have the capacity to invade the four main Japanese islands, the occupation of “islands at the southwestern end of the archipelago is becoming a realistic possibility.” Moreover, Japanese ARDB advocates stress the opportunity for enhanced U.S.-Japanese amphibious cooperation. Some U.S. experts also welcome the emergence of a “Marine-like” JSDF capability as a means for Japan to become a more useful ally for the United States by alleviating critical U.S. amphibious shipping shortfalls and by contributing to an “amphibious architecture” to counter China’s “grey-zone” activities across the Western Pacific.



However, this paper argues that Japan’s amphibious capability faces major strategic and operational challenges. The central question is which strategic-operational objectives the ARDB is supposed to serve and whether those goals are achievable in a rapidly changing operating environment for amphibious forces. Posing this question delivers a less convincing picture of the strategic utility of the ARDB in its present focus and configuration.

While Japan’s ARDB can certainly play a useful role in humanitarian assistance/disaster relief and noncombatant evacuation operations, there has been little rethinking inside the JSDF about the implications of a rapidly shifting operating environment for amphibious forces in high-end scenarios. Indeed, the continued utility of amphibious forces in highly contested environments is not a given.

The ARDB’s current narrow strategic focus on amphibious warfighting operations to “retake islands” neglects China’s increased ability to target high-signature military targets such as big amphibious ships and support elements. In addition, Japan’s amphibious capability remains nested in a risky, potentially outdated defense strategy for deterring China’s growing military power. Moreover, operationally the ARDB is too small and vulnerable in high-end scenarios involving China. There remain unresolved JSDF issues regarding jointness and sustainability for such highly complex operations.

If these issues remain unaddressed, Japanese strategic decision-makers run a serious risk of the amphibious force becoming strategically obsolete in the event of a shooting war with China. Japanese defense planners should consider working toward an “ARDB 2.0” that has a lesser focus on “retaking islands” and applies a more flexible approach and structure as part of a maritime denial strategy. Rather than simply assuming that amphibious forces are the optimal solution for defending Japan’s many islands, the JSDF should rigorously wargame those assumptions and consider alternative options. After all, developing amphibious capability is neither institutionally nor financially cheap, and those investments might be better made elsewhere.

Moreover, Japanese defense policymakers need to carefully consider the alliance dimension of the amphibious capability. While the ARDB might see a rationale for aligning itself closely with the U.S. Marine Corps for reasons of interoperability and defense budget allocations, mimicking the Marine Corps in operational planning and structure has limitations given Japan’s specific focus on “island defense.” Japan and the United States should cooperate closely on adjusting their respective amphibious forces for operations in contested environments through trade of comparative advantages that would serve both Japan’s future ARDB as well as potential joint amphibious operations.

What’s It For? Considering the Strategic Utility of Japan’s Amphibious Force

It seems odd to question Japan’s amphibious force development. After all, Japan is an archipelagic island nation and has many islands to defend. Moreover, the Indo-Pacific is in the midst of an “amphibious renaissance” with many other nations including China, South Korea, Australia, India, and several Southeast Asian countries investing in amphibious capabilities. Advocates point to the diverse operational spectrum for amphibious forces in what is primarily a maritime theatre, ranging from humanitarian assistance/disaster relief to noncombatant evacuation operations, countering “grey-zone” activities, and high-intensity warfighting. Still, it is critical to examine Japan’s specific strategic context and question the strategic rationale for investing significant financial and personal resources in a highly complex military capability.

Undoubtedly, some amphibious capability makes sense for Japan, particularly given the country’s vulnerability to natural disasters such as the Great Tohuku Earthquake of March 2011. But optimizing amphibious forces for high-intensity operations, including major financial investments in large amphibious ships and the specialized soldiers required to operate them, is a different equation given the considerable strategic and economic trade-offs. In Australia’s case, for instance, critics have questioned the rationale for the Australian Defense Force’s current ambitions for amphibious warfare in tandem with its the U.S. ally in the absence of realistic operational scenarios. Australia’s amphibious force is very small and might be better off conducting humanitarian assistance/disaster relief and noncombatant evacuation operations with smaller, much less expensive platforms. While Japan’s strategic environment is different given its geostrategic proximity to China, similar questions can be raised. In fact, precisely because the need to directly deter (and potentially fight) Chinese forces is much higher for the JSDF, the strategic rationale for building amphibious forces for that purpose deserves greater scrutiny.

The starting points for assessing Japan’s current amphibious warfare plans and structure are assumptions about the future utility of amphibious operations in highly contested environments. In Japan’s case, this means considering the impact of China’s increasingly sophisticated and expanding anti-access/area denial (A2/AD) capabilities, which pose serious strategic and operational challenges to Japanese and forward-deployed U.S. forces. This is not to argue that Japan and its American ally have no means of countering China’s A2/AD posture. Quite the contrary: Opportunities exist to “turn the tables” against the PLA and develop allied A2/AD structures that negate PLA advantages of geography and precision missile strikes. Amphibious forces will have a role in such a posture. But as the new Marine Corps Planning Guidance by Commandant Gen. David Berger makes clear, the service risks losing relevance in U.S. strategy unless it rethinks and reshapes its role and structure to reflect the changing operating environment of the Pacific region.

Japan’s defense planners also need to reassess the strategic utility of amphibious forces. To be sure, the ARDB does not share the U.S. Marine Corps’ broad mission spectrum within the context of U.S. expeditionary naval warfare. Japanese experts are at pains to emphasize that the emerging amphibious force is “not expeditionary” and that its purpose is only “to strengthen the ability of the JSDF to deter Japan’s adversaries, and, if necessary, defend and secure Japan’s islands.” Major General Takanori Hirata, the current commander of the ARDB, stated that “island defense” was “more and more key” to Japan’s strategic planning and the role of the amphibious force.

However, this focus on “island retaking” could exacerbate existing problems, particularly if Japan’s amphibious force remains centered around relatively large signature ships operating within the PLA’s inner “threat ring” of precision strike systems — an area which includes the Nansei Islands. The PLA’s investment in submarines, anti-ship cruise and ballistic missiles, tactical combat aircraft, and maritime domain awareness will enable it to detect and target formations of Japanese (and U.S.) ships operating around the island chain. In contested A2/AD environments, opposed beach landings using amphibious assault could become too risky and even untenable.

This new operating environment for amphibious forces operating in close vicinity to China has strategic ramifications for Japan. Chief among those is the very ability of the ARDB to achieve the desired strategic effect: deterring and defending the many islands in the Nansei Island chain against PLA aggression. Critically, the ARDB is nested within a defense strategy that appears in need of adjustment. In the early 2000s, Japanese defense planners identified the defense of remote islands as the amphibious force’s main mission. As analysts have pointed out, the JSDF remains postured for a “forward defense” strategy, centered on the objective to defeat PLA forces “quickly and thoroughly before they can gain entry into the country — or, failing that, shortly thereafter.” In this forward-oriented defense posture, the ARDB would spearhead an “early counterattack to retake islands occupied in a potential Chinese fait accompli.”

However, this strategy is predicated on the JSDF’s capacity to deploy and sustain forces superior to the PLA — an increasingly problematic assumption given China’s growing ability to project significant power in these areas at the start of a major conflict. As Eric Heginbotham and Richard Samuels point out, while in a conflict with the PLA, the JSDF would “ultimately have to retake lost ground[;] a premature Japanese counterattack against Chinese forces on the Senkaku Islands — or on small islands at the southwestern end of the Ryukyu chain — would court military disaster.” Such operations would be a major military undertaking requiring key naval, air, and amphibious assets to operate jointly across stretched supply lines and within the highest A2/AD threat rings presented by PLA weapons systems. Opposed landings by the ARDB would require not just the “finely orchestrated application of force, but also protracted maintenance of air and sea control in the immediate vicinity — turning mobile assets into fixed or semi-fixed targets for the adversary’s submarines, aircraft, and ground-launched missiles.”

Developing this level of JSDF operational art would require a significant investment of time and money. Currently, the ARDB faces significant capability shortfalls to realize its operational objectives to “retake” islands in the Nansei Island chain. Its amphibious capability is centered around only a few large and vulnerable principal amphibious ships: Only three Osumi-class amphibious landing ships and six landing craft air cushion vehicles are dedicated amphibious ships. While they could be supported by two Hyuga-class and two Izumo-class helicopter destroyers, those vessels were not specifically designed for amphibious operations. To be sure, the planned conversion of the Izumo-class helicopter destroyer into small aircraft carriers to operate a number of short takeoff and vertical landing F-35B Joint Strike Fighters could theoretically enhance the JSDF’s capability to provide greater air mobility and close air support for its landing force — although the conversion would be very costly and reduce the vessel’s utility for other critical missions such as anti-submarine operations. Similarly, the acquisition of Osprey tilt-rotor aircraft could facilitate the ship-to-objective movement of amphibious troops onto those islands. Japan has announced it will extend the range of its land-based anti-ship missiles and deploy those systems on its key islands across the chain.

Still, the JSDF’s amphibious posture would remain focused on a few large, signature platforms. The JSDF would struggle to muster the levels of jointness required to conduct complex amphibious operations in highly contested environments. One shortcoming is the lack of effective mechanisms to enable true jointness and command and control between the different arms of the Japanese military. It is far from clear, for instance, that the Japan Maritime Self-Defense Force and Air Self-Defense Force would be comfortable allowing the Ground Self-Defense Force to command their units in a supporting role. In fact, no joint doctrine for such operations exists at present, and there is looming suspicion among senior Japan Maritime Self-Defense Force officers that the ARDB is predominantly the result of Ground Self-Defense Force lobbying rather than an operational necessity.

True or not, interservice mistrust over the true purpose of the amphibious capability will be hard to overcome. It will also make addressing the challenge of coordinating joint fires, specifically close air support for a future landing operation, difficult. The Air Self-Defense Force’s mission has remained concentrated on air defense tasks and has not been conceptually integrated into Ground Self-Defense Force and Japan Maritime Self-Defense Force thinking and planning for amphibious operations. Significant trust issues between the Ground Self-Defense Force and the Air Self-Defense Force in regard to close air support would need to resolved, and some Japanese defense experts believe F-35B jump jets should be assigned to the Japan Maritime Self-Defense Force rather than the Air Self-Defense Force to minimize this problem. A heavily scripted exercise culture within the JSDF is also not conducive in this context, nor is the lack of large-scale joint exercises for amphibious operations.

Finally, a RAND study identified significant equipment shortfalls in Japan’s nascent amphibious force for “island retaking” missions. For instance, both the Hyuga and Izumo helicopter destroyers are limited in numbers and lack floodable well decks to operate amphibious assault vehicles and landing craft air cushion vehicles. The three Osumi landing ships also have limited utility as main ship-to-shore connectors in high-intensity environments given their lack of storage, fitting only two landing craft air cushion vehicles, and because they are not optimized for the JSDF’s amphibious assault vehicles. The deeply entrenched individual culture of the three services has contributed to a limited willingness to invest in smaller and faster ships designed for rapid deployment of ground forces. For instance, the Japan Maritime Self-Defense Force remains wedded to its traditional focus of assisting the U.S. Navy and a desire to invest in major surface combatants and submarines. As a result, in its current configuration, the JSDF seems ill-prepared to conduct complex amphibious operations in defense of its many islands.

Toward “ARDB 2.0”?

Tokyo needs to plan for greater defense self-sufficiency, not least since the Trump administration’s policies have left all of America’s Pacific allies wondering just how steadfast U.S. defense commitments really are in the age of “America first.” Incrementally, the JSDF is taking steps for operating in a very different future environment, although Japan’s political strategy remains centered around the expectation that the U.S.-Japanese alliance will remain the cornerstone of the country’s defense. But the experience with the Trump administration has left the Japanese government more concerned than ever about the future of this alliance.

In this context, the development of the amphibious capability is being presented by parts of the JSDF, strategic policymakers, and the expert community as a stepping stone to enabling greater independent defense capability and enhanced opportunity for U.S.-Japanese (and possibly Australian) amphibious cooperation. However, it is doubtful whether the ARDB and its supporting elements are “fit for purpose” given a changing operating environment for amphibious forces. The ARDB’s focus on “island retaking” disregards China’s ability to pose a major and increasing threat to large amphibious formations and supporting elements. Indeed, it is remarkable how little debate there is in the Japanese strategic community about the future utility of the ARDB in a high-risk environment.

To avoid the associated risks of strategic obsolescence, Japan should rethink the future of “amphibiosity” in its evolving defense strategy. Unless Japanese defense planners can demonstrate through sophisticated, unscripted joint exercises and simulations how the ARDB and JSDF could realistically achieve the desired strategic-operational objectives under conditions of advanced PLA A2/AD threats — and without the support of U.S. forces — Tokyo should consider launching “ARDB 2.0.” This approach would start from the premise that amphibious forces can indeed play a role in the defense of Japan but that in order to do so a less static focus on “island retaking” centered around a few large, signature platforms is needed. Amphibious force employment should be conceived as part of an “active denial” defense strategy that emphasizes a buildup of a more resilient Japanese capability to frustrate PLA power projection in a prolonged campaign rather than seeking its early, swift defeat in the inner A2/AD threat ring.

Instead of wargaming how to “storm the beach,” the Japan Maritime Self-Defense Force should focus on how to utilize the amphibious force as part of a strategy to exploit PLA weaknesses. Not only could the JSDF (in combination with U.S. forces) pose formidable maritime and air denial threats to advancing PLA forces, PLA forces would also find it very difficult to sustain their presence on even smaller occupied Japanese islands in the Nansei Island chain. Japan’s amphibious force might be better placed to operate as part of a fully integrated naval strategy, designed to pose multiple maritime A2/AD threats to the PLA across its island chain. Such a focus might also mean the ARDB becomes an arm of the Japan Maritime Self-Defense Force, rather than the Ground Self-Defense Force, to reduce friction and grow jointness organically. The ARDB would also need to reduce its reliance on large, vulnerable ships and instead experiment with more and smaller platforms (including commercial ships). Just like the U.S. Marine Corps, Japanese amphibious forces need to become more resilient, flexible, and dispersed in order to deny the PLA maritime operating space. This would include a greater focus on smaller, more expendable, and less expensive platforms, as well as the introduction of new innovative technologies.

Conceptually, rather than seeking to mimic the U.S. Marine Corps on a smaller scale, Japan’s amphibious forces should conceive of themselves as elite amphibious commando units or “marine raiders.” They would then be charged with alternative amphibious missions in a broadened concept of “island defense.” For instance, operating in faster and smaller vessels, they could be used to deploy highly mobile anti-ship or antiair weapons systems on island features and floating platforms, including commercial vessels, to present additional challenges for the PLA as part of an overall JSDF maritime denial campaign. Moreover, as a specialized amphibious light infantry, an “ARDB 2.0” could be employed in a strategy to isolate and erode PLA forces after they have landed on Japanese islands. Such forces would be more akin to special operations forces instead of the current figuration as a medium-weight amphibious force.

Crucially, the JSDF could utilize its close ties with the United States (and the U.S. Marine Corps in particular) to rethink and reconfigure its amphibious force for operations in contested environments. As mentioned before, the U.S. Marine Corps is going through a process of fundamental review of its modes of operations in the face of China’s challenge. And there is an expectation that U.S. and Japanese marines would fight in separate battle spaces but in synchronized fashion. Arguably, a lighter but more versatile JSDF amphibious force could provide a comparative advantage for alliance operations. It could also be more effective in a stand-alone Japanese defense strategy against the PLA.

As with Gen. Berger’s directive, it is far from certain whether the JSDF will muster the cultural shift required to fundamentally rethink and adjust its amphibious capability. Indeed, because of the substantial lack of JSDF joint capability development and the influential role of the Ground Self-Defense Force in defense capability decisions, there is a high probability that the ARDB will not change much in terms of conceptual focus and configuration. While a “sunk cost” approach to Japan’s amphibious capability would be neither surprising nor unprecedented, the ARDB would risk obsolescence in contingencies involving the defense of the Nansei Island chain against serious threats posed by the PLA.



Benjamin Schreer is professor and head of the Department of Security Studies and Criminology at Macquarie University, Sydney, Australia.

Image: U.S. Marine Corps (Photo by Gunnery Sgt. Ismael Pena)