Japan’s Defense Priorities and Implications for the U.S.-Japan Alliance

This commentary is part of the Exploring New Horizons: Japan’s Defense Priorities project, a CSIS Japan Chair initiative featuring analysis by leading Japanese and American scholars examining the implications of Japan’s new national security and defense strategies and opportunities for bilateral cooperation.

The government of Japan is to be commended for its action, leadership, and vision in light of security developments in the Indo-Pacific and elsewhere. The release of the second National Security Strategy (NSS), along with a National Defense Strategy (NDS) and Defense Buildup Program (DBP), on December 16, 2022, is a pragmatic response to growing security challenges coming from every possible vector, including China, North Korea, and Russia as well as threats from the cyber domain.

Japan’s former policy to restrict the defense budget to 1 percent of GDP, while not always adhered to, guided government decisionmaking for far too long. Prime Minister Kishida Fumio has established a new target for military spending over the next five years: ¥43 trillion ($315 billion), or 1.5 times the current level. Japan plans to increase its defense budget in the next 5 to 10 years to about 2 percent of GDP, congruous with the agreed-upon but not uniformly adhered to NATO standard, as North Korea’s threats and China’s territorial assertiveness increase.

The Japanese government’s commitment to unprecedented defense and security reforms and investments puts Japan at a historic inflection point. The NDS (formerly known as the National Defense Program Guidelines) and DBP (formerly known as the Mid-Term Defense Program) outline required defense capabilities to implement the NSS and acquisition priorities for the next five years, respectively. These documents will guide the Ministry of Defense’s priorities in spending across seven broad areas of focus as described in the NDS: (1) stand-off defense capabilities; (2) integrated air and missile defense capabilities; (3) unmanned defense capabilities; (4) cross-domain operation capabilities; (5) command and control and intelligence-related functions; (6) mobile deployment capabilities and civil protection; and (7) sustainability and resiliency. This ambitious agenda is laudable yet fraught with potential problems. Namely, with so many priorities, the axiom of “when everything is a priority, nothing really is” comes to mind. 

It bears remembering and reinforcing that Japan is not in this completely alone and that Japanese priorities, while sovereign, should be nested in the combined strength of its bilateral alliance with the United States. While Japan could unilaterally decide which capabilities to acquire, which reforms to undertake, and which new operational concepts to adopt, it would be ill-advised not to involve its key ally in the prioritization process.

The historic changes in Japanese strategy and policy should be applauded by the United States. In particular, an increased defense budget and the acquisition of a counterstrike (i.e., offensive) capability. Now the real work begins, and it has to start with a realistic prioritization by the Japanese government, and the Ministry of Defense specifically, of defense investments. 

Cross-cutting the seven areas of focus in the Japanese NDS, the priorities should be pared down into actions that can be accomplished in the next several years. These priorities can be divided into the following overarching categories: command and control, strike capabilities, and readiness.

Command and Control

The Japan Self-Defense Forces (JSDF) and U.S. forces need to be more fully integrated to be able to engage adversaries effectively and efficiently. Enhancing and modernizing command and control (C2) structures and systems will strengthen interoperability within the alliance. In fact, C2 improvements are fundamental to ensuring the effective employment of JSDF strike capabilities, which should be a top priority. One without the other makes little operational sense. It is not practical to assume optimization of new strike capabilities if sensor-to-shooter integration, systems compatibility, and C2 are not addressed in a deliberate manner within the alliance construct. 

Structurally and organizationally, the JSDF should establish a permanent Joint Headquarters, as outlined in the NDS, sooner rather than later. A joint command structure atop of the individual Japanese armed services has been missing and would significantly aid in coordination with U.S. forces in a contingency. Such an architecture would foster greater jointness, something that is currently lacking in the JSDF, as well as engender greater interoperability with the United States. In fact, the establishment of a Japanese Joint Headquarters should include the assignment of not only U.S. liaison and exchange officers but also the same from countries such as Australia, South Korea, the Philippines, and perhaps even some European partners. This is very similar to the presence of foreign military officers at U.S. Combatant Commands. Not only would there be operational benefits from including a cross-section of like-minded countries, a Joint Headquarters would also signal to potential adversaries that other countries are vested in Japan’s defense.

Relatedly, the United States needs to reexamine whether the size, composition, and mission of Headquarters U.S. Forces Japan (USFJ) is adequate given the evolving and growing security challenges. The headquarters’ strength of approximately 160 personnel may no longer be sufficient to address current and future requirements associated with the Japanese establishment of a Joint Headquarters. Moreover, consideration should be given to integrating U.S. staff with a counterpart Japanese headquarters. Embedded U.S. staff with access to both U.S.-only and bilateral information systems would enable Japan’s capabilities in joint fires (including targeting), cyber, space, and intelligence, surveillance, and reconnaissance (ISR). In the future, the alliance should also consider the placement of a U.S. commander with some operational authorities beyond those currently invested at USFJ, in order to enable the type of unified action that may be needed in a future security crisis. Certain aspects of the U.S.-Republic of Korea Combined Forces Command model may be applicable.

The effectiveness of new command structures and operational relationships and responsibilities can be significantly enhanced by modern C2 systems. There are several C2 systems that the United States is using that should be offered to Japan for priority procurement. 

The United States should approve and facilitate Japanese acquisition of the Cooperative Engagement Capability (CEC) as its sensor network to allow for an integrated fire control capability. The Japan Maritime Self-Defense Force (JMSDF) is the most capable allied navy in the Western Pacific. It operates Aegis-equipped destroyers as well as E-2D battle management and sensor fusion aircraft. Notably, these are platforms that the U.S. Navy deploys and has forward stationed in Japan, all of which utilize CEC. If CEC were utilized by both the JMSDF and the U.S. Navy, both navies could link their sensors together to provide for integrated targeting and fire control. This would undoubtedly provide greater coverage, greater stand-off capability, more effective fire control, and overall improved interoperability. 

Similarly, Japan should acquire the Integrated Air and Missile Defense (IAMD) Battle Command System (IBCS) to modernize its ability to intercept enemy missiles and aircraft. This system, currently being fielded in the United States and Poland, is based on an open-architecture format, allowing for the integration and utilization of “any sensor” and “best shooter” to intercept. This attribute is growing in importance given the diversity of missile and air threats as well as the inverse cost curve involved when shooting potentially low-cost threats with high-cost missiles. IBCS would facilitate Japan integrating its disparate sensors and shooters within its own Japan Aerospace Defense Ground Environment (JADGE) system. Moreover, it would also permit potential integration with U.S. systems. Such an open-architecture approach would be the foundation for a more seamless employment of alliance assets than is currently the case. The result would be an improved combined Japanese-U.S. IAMD capability that would incorporate existing capabilities into a more effective bilateral operational approach.

Strike Capabilities

The fragility of deterrence was unfortunately proven by the inability to prevent the Russian invasion of Ukraine. Destabilizing rhetoric accompanied by continued aggressive actions by and provocative deployments of Chinese, North Korean, and Russian forces accentuate the military threat to Japan. Deterrence will be significantly enhanced if Japan is able to credibly demonstrate that it will be able to strike China, North Korea, or Russia if attacked. The JSDF needs an ability to put at risk a potential aggressor’s homeland in response to offensive action initiated by Beijing, Pyongyang, or Moscow. The most expeditious and effective manner to accomplish this is by acquiring a currently available long-range strike (or counterstrike) capability. In the short run, this would necessitate procurements from U.S. suppliers. However, Japan should also seek an indigenous production capability or even team with another partner country to co-develop and co-produce a long-range strike missile. The latter could potentially even be the entrée to Japan-AUKUS cooperation. The U.S.-Japan SM3, Block IIA ballistic missile defense interceptor is perhaps an example worth emulating in a future strike capability involving two or more defense industry partners. Possible U.S.-Japanese co-development of a hypersonic missile defense capability, the Glide Phase Interceptor (GPI), could be a positive step as well. 

Japan plans to bulk order 400 Tomahawk Land Attack Cruise Missiles (TLAMs) by early 2023. While a strong start, this quantity is insufficient. As seen in U.S. interventions in the Middle East as well as in the war in Ukraine, 400 missiles will not last long in a high-end fight. The daily headlines from the war in Ukraine indicate potential challenges associated with procurement in sufficient numbers of all types of munitions. Japan, with U.S. government support and encouragement, should prioritize early and robust acquisition of TLAMs to fill gaps now. 

Additionally, the JSDF should be equipped with the Long-Range Anti-Ship Missile (LRASM), Joint Air-to-Surface Standoff Missile-Extended Range (JASSM-ER), Naval Strike Missile (NSM), and Joint Strike Missile (JSM). These types of missiles would be of particular utility in an East China Sea or Taiwan contingency against China’s People’s Liberation Army Navy. In conjunction with the United States, as well as other partners and allies, bulk orders of these systems should be considered to maximize economies of scale, lower overall costs, and share risk among like-minded countries. Such an approach will require additional coordination between relevant capitals but could serve as a valuable precedent for future acquisitions, given the challenges that the war in Ukraine continues to highlight. 

The United States has a key role to play in facilitating priority acquisitions for Japan and other allies. Current U.S. government practices, processes, and procedures related to technology release, foreign military sales, and other issues related to International Traffic in Arms Regulations (ITAR) should be modernized to address the unprecedented defense challenges that the United States and its allies face. To be clear, that is not justification for taking security shortcuts. However, political leadership is required to ensure bureaucracies and institutions are incentivized toward a bias for action and “yes” answers, as opposed to a default of “no.” Incidentally, success for AUKUS is predicated on same concept and hopefully will serve as the catalyst for wide-ranging reforms.


Beyond tables of organization and equipment, how a military is prepared to fight is best predicted by how it trains and operates in peacetime. On paper, the Russian army should have been able to take Kyiv last March. The reality on the ground, however, was very different and a reflection of poor, unrealistic training and preparation as well as other factors. Japan, with its new NDS and DBP, has very publicly committed to major defense budget increases, a decision which is to be lauded. It bears reinforcing that platform acquisitions, while critical, are only part of the equation. The manner in which JSDF personnel train on these platforms is equally important and foundational to a robust deterrent posture.

In that same vein, Japan needs to enhance the overall training of the JSDF in high-end warfare. The realities of modern warfare require the JSDF to conduct training and exercises in combined arms and joint operations much more vigorously than is currently the case. That will require greater time in the field, expansion of training areas and ranges, expending more live rounds of all types, and increasing the scope and complexity of joint and combined exercises and operations. Furthermore, USFJ must be able to train as they would be forced to fight in the region.

While there are clear geographic limitations and issues related to population density on the Japanese islands, Japanese forces need to be able to conduct realistic training and exercises, particularly at night, with live ammunition, in all domains, and at various altitudes. Local politics and its national implications for the governing party have been a severe constraint in this regard. However, a robust and candid national conversation in Japan has become indispensable to explain to the Japanese people that sacrifices and compromises are required by all in order to strengthen deterrence. Some restrictions will always remain, but they must be reduced. Those that do remain should be addressed by increased JSDF deployments to locations in the United States and or Australia, where appropriate training ranges are available.

A subcomponent and significant contributor to readiness is logistics in preparation for a possible contingency. In the short term, a logistical buildup should focus on Japan’s southwest islands. The most likely scenarios of Chinese aggression are against the Senkakus and across the Taiwan Strait. This will most certainly implicate Japanese responses from its military bases and outposts in the Ryukyu or Nansei Islands. In order to hedge against such a crisis, pre-positioned stocks of water, food, medical supplies, fuel, munitions, and other key materials should be amassed in the island chain. This would allow for troops to fall in on capabilities already forward deployed in times of crisis. This would also allow for limited transportation assets to be focused on personnel movements in a contingency instead of also having to move supplies. Moreover, these contingency stocks could also be utilized in case of a natural disaster response scenario.

It is noteworthy that the Japanese fiscal year 2023 budget does focus heavily on related readiness priorities, including spare parts, maintenance, ammunition, and hardening of sites and bases. This is a laudable and appropriate start. Longer-term commitments to these priorities to ensure that readiness is maintained and enhanced will only be revealed in future budget cycles. 

The Future

It bears repeating that Japan has made historic and tough decisions to enhance deterrence against threats emanating from a variety of malign actors. While that should be commended at every opportunity, much remains to be done beyond those policy pronouncements and published plans. Prioritized implementation is the critical factor. 

Fundamentally, the strength of the U.S.-Japanese alliance as a whole is the greatest bulwark against aggression. The United States and Japan need to be prepared to continuously ensure that the alliance is match fit for the future, particularly as adversaries continue to grow and diversify their capabilities. Eventually, the United States will need to pursue diverse force posture opportunities that will strengthen its ability to operate forward and more flexibly with allies and partners.

This is a tough issue that requires attention from national leadership as well as increased cooperation. With continued work on new joint warfighting concepts will inevitably come changes to U.S. military structures and how they train, equip, organize, deploy, and fight. This will, and should, impact the U.S. component of the alliance on the ground in Japan and elsewhere in the Indo-Pacific. The United States needs to be frank about the capabilities needed by the alliance on an operational level and then determine how the alliance can best meet the challenges of today and tomorrow.

Heino Klinck is a senior associate (non-resident) with the Japan Chair at the Center for Strategic and International Studies (CSIS) and former deputy assistant secretary of defense for East Asia.

This project is made possible with support from the Government of Japan.

Heino Klinck
Senior Associate (Non-resident), Japan Chair