Enhancing U.S.-Japan Alliance Command and Control Relationships

The security environment surrounding Japan is deteriorating more than ever before. China has increased its military activities in the East China Sea in recent years, including incursions into the airspace near Taiwan since U.S. House Speaker Nancy Pelosi’s visit last August. North Korea is launching ballistic missiles with record high frequency while advancing its technological capabilities, including irregular trajectory to break through Ballistic Missile Defense (BMD) systems. And Russia is attempting to change the status quo by force with its invasion of Ukraine, which has heightened concerns in Japan and other countries about the potential implications of the war for security in Asia.

In the face of this increasingly complex security environment, the Japanese government led by Prime Minister Kishida released a new National Security Strategy, National Defense Strategy, and Defense Buildup Program last December. In these strategic documents, the Japanese government announced that it will fundamentally reinforce Japan’s defense capabilities and strengthen deterrence by introducing counterstrike capabilities, which had been labeled “enemy base attack capabilities” in Japan’s defense policy debate.

The recent discussion of “enemy base attack capabilities” stems from a debate in the 1950s about whether overseas deployment was permissible for the Self-Defense Forces (SDF). During that debate, the government of Japan testified that such capabilities were constitutional, provided that such an attack would be limited to the minimum extent necessary to prevent a missile attack against Japan, as long as an armed attack against Japan has occurred. The debate has resurfaced due to North Korea’s repeated missile launches and nuclear tests since the 1990s. Although Japan has improved its BMD capabilities, BMD alone is no longer sufficient for Japanese defense. More recently, proponents of Japan acquiring counterstrike capabilities have emphasized the potential to complement U.S. capabilities and serve as an effective deterrent against China, which has boosted its intermediate-range missile capabilities and is strengthening its anti-access/area denial (A2/AD) capabilities to counter U.S. power projection in the region.

The Kishida administration states that despite Japan’s intent on acquiring counterstrike capabilities, the division of labor under the U.S.-Japan alliance will remain the same. This seems to imply that the primary role of the SDF will remain the defense of Japan, even after Japan recognizes its own counterstrike capabilities. Japan has already begun to procure and develop multiple long-range missiles, which to varying degrees will require the SDF to cooperate with U.S. forces in many areas, including targeting. (A prime example is Japan’s recent decision to purchase Tomahawk missiles.)

Reviewing Command and Control Relationships Is the Key for Deeper Cooperation

Japan’s acquisition of counterstrike capabilities will have a positive impact on the U.S.-Japan alliance in many respects. Attacking a target at a distance requires a large-scale system that includes everything from identification of a target to post-attack evaluation. Japan, for its part, will be looking to the United States to provide support to develop the requisite infrastructure. With more robust U.S.-Japan cooperation, joint operations in any situation will improve, and that will enhance deterrence. Bolstering the alignment of U.S.-Japan command and control (C2) relationships is therefore one of the most critical areas for the U.S.-Japan alliance to address. Both countries seem to recognize this given that a joint statement released after the recent U.S.-Japan Security Consultative Committee (2+2) meeting includes a commitment “to exploring more effective Alliance command and control relationships to enhance interoperability and responsiveness.”

Bilateral dialogues such as defense ministerial meetings and joint senior leaders’ seminars are held regularly, and several joint exercises have been conducted on a bilateral and multilateral basis. In November 2022, the SDF and U.S. forces conducted Keen Sword 23 focused on maritime operations using Japanese surface-to-surface missiles (SSMs) and the U.S. High Mobility Artillery Rocket System (HIMARS), which illustrates stronger allied capability and suggests potential to coordinate counterstrike operations. As to the structure of military cooperation, it is effectively multilayered to ensure consistent operations. Multiple consultative bodies operate from peacetime, including the Bilateral Joint Operation Coordination Center (BJOCC) at Yokota Air Base, which plays a substantial role for effective coordination including air defense operations.

Bilateral alliance cooperation, ranging from the political level to the operational level, takes place under a parallel C2 structure. The first question that comes to mind when considering how to better integrate alliance C2 relationships is whether to integrate operational control (OPCON) of the two militaries by transferring OPCON from one ally to another in certain contingencies.

Conventional Hurdles in Transferring OPCON

When countries make joint decisions and convert them into military operations, it is generally more efficient to have a combined command with one country having an integrated OPCON for both countries’ forces. For example, the North Atlantic Treaty Organization (NATO) and U.S.-Republic of Korea (ROK) alliance hold well-structured and efficient C2 capabilities for military operations. Moreover, integrated C2 is becoming more critical in a complex security environment where different situations could occur simultaneously and require multi-front operations.

Then why is C2 not integrated under the U.S.-Japan alliance? During the Cold War, Japan was arguably concerned about becoming entrapped in a U.S. conflict that might entail the unconstitutional use of force. Under Article 9 of the constitution, Japan may not use force unless there is an armed attack on Japan. (Under the 2015 Peace and Security Legislation, the use of force is possible even in the event of an armed attack against another country with which Japan has a close relationship and the existence of Japan is threatened by such an attack.) Therefore, if there was a U.S.-Japan combined command headed by a U.S. military officer, and a Japanese national was involved in operational planning for use of force that does not meet the requirements of Japanese law, the Japanese planner would have been considered complicit in the unconstitutional use of force even if the SDF were not involved in the operation. This is not merely a matter of Japan’s constitutional constraints but also differing missions between Japan and the United States, as noted in Article 6 of the U.S.-Japan Security Treaty, which states that the United States will not just defend Japan but also contribute to “the maintenance of international peace and security in the Far East.” Another possible explanation from Japan’s perspective is the political impact of giving control of the SDF to another country. In fact, the argument emphasizing Japan's sovereignty and independence with respect to combined command seems to have been a primary focus immediately after the establishment of the SDF in 1954.

Legal and Operational Reasons Not to Pursue Integrated OPCON

There are other hurdles that would also complicate any effort to integrate OPCON under the U.S.-Japan alliance. For example, Japanese law presumes that all SDF units are strictly incorporated into and controlled by a chain of command headed by the prime minister. This means that legal action would be required even if only a partial transfer of OPCON were to be considered. Japan established a framework for practically transferring OPCON to the United Nations for peacekeeping operations (PKO) in the “PKO Law” passed by the Diet in 1992 after a heated debate that divided public opinion. And the PKO law introduced complex administrative procedures that could undermine operational flexibility. This intricate system only works under the PKO law, which assumes a situation without the use of force. Such a framework may not be appropriate in a contingency where the situation is changing rapidly. Japan would therefore have to create an entirely new legal framework for transferring OPCON to another country, which would likely take years to introduce. But the security environment around Japan is evolving rapidly and therefore renders such traditional administrative procedures impractical.

Legal challenges could also complicate the exercise of counterstrike capabilities. Under Japan’s constitution, the use of force must be to the “minimum necessary” extent, and this would be no exception for counterstrike capability. The use of such capabilities would depend on a political decision in accordance with each specific situation, thereby making it extremely difficult to align alliance prerogatives in advance. Also, it is natural for Japan to be politically more cautious than the United States, simply considering Japan’s relative inexperience with military operations. Therefore, incorporating highly political decisions into a military operation under integrated OPCON could seriously disrupt future operations.

From the operational point of view, allied C2 capability should be effective not only in war time but also in peacetime and should function seamlessly in a variety of circumstances including gray zone situations that fall short of conflict. But this requirement collides with likely resistance in Japan to the notion of ceding control of the SDF to another country.

In light of these hurdles, the C2 relationship between the United States and Japan should be improved without integrating OPCON of both parties. Possible options could include establishing a joint operation coordination center that allows both parties to work shoulder to shoulder for all operations around Japan. U.S. Indo-Pacific Command (INDOPACOM), which is responsible for cooperation with the SDF in case of an emergency around Japan, is based in Honolulu. The SDF selects responsible operational headquarters at the local level on a case-by-case basis. Therefore, a coordination center for alliance C2 can only be realized through organizational restructuring in both militaries. Given operational and geographical factors, stationing both U.S. and Japanese staff under a joint operational headquarters in Japan should be the first option to pursue. While having the coordination center in the same building would be a great leap for the alliance, even if it was in separate buildings, physical proximity would greatly improve communication between two parties.

Homework for Each Country

It is necessary to promote discussion of the following points to enhance alliance coordination under a parallel C2 structure.

For Japan, establishing a permanent joint headquarters (PJHQ) for the SDF, as declared in the new National Defense Strategy is an urgent task. Without that, a regional service headquarters would command temporarily organized combined task forces whenever a situation arises, but it is difficult to respond to complex situations with such a posture. Since having a PJHQ would facilitate effective coordination with the U.S. side, no matter where it will be located, Tokyo should bear in mind the importance of the joint operation coordination center concept.

The challenge for the United States is the status of U.S. Forces Japan (USFJ), which, unlike U.S. Forces in Korea, is not designated as a warfighting command but rather focuses mainly on maintaining and improving the readiness of U.S. forces in Japan through proper administration of the Status of Forces Agreement and close communication with the Japanese government. As Japan considers a more joint C2 structure for the SDF, the United States also needs to consider rearranging geographical allocation of its warfighting commands in the Indo-Pacific. To maximize the efficacy of operational cooperation, INDOPACOM should establish a subordinate organization in Japan to control U.S. military operations around Japan and have it play a role of operational coordination with the SDF in the joint operation coordination center.

Discussions of changes in the C2 relationship between Japan and the United States including legal issues have received relatively little attention. Given the complexity of both the regional security environment and the C2 debate, more bilateral dialogue will be essential to objectively analyze the advantages and disadvantages from both political and military perspectives.

Yohsuke Aoki is a visiting fellow with the Japan Chair at the Center for Strategic and International Studies in Washington, D.C.

The views expressed herein are solely the author’s and do not represent the views of the Japanese Ministry of Defense, nor the government of Japan.

Yohsuke Aoki

Visiting Fellow, Japan Chair