Strategic Deepening of the Japan-U.S. Alliance: New Horizons of Security Indicated by Joint Missile Production and AI Target Selection Systems

The Japan-U.S. summit scheduled for March 19, 2026, is likely to become a historic turning point in the security cooperation between the two countries. In this meeting between President Trump and Prime Minister Sanae Takichi, three pillars are expected to be discussed: the expansion of military information sharing, the establishment of a target selection system utilizing artificial intelligence, and the joint production of missiles. These initiatives symbolize not just a strengthening of defense cooperation but also a qualitative transformation of the Japan-U.S. alliance.

According to reports from Kyodo News, the U.S. military and the Japan Self-Defense Forces are planning to build a system that efficiently selects attack targets using classified information and AI. This technological innovation has the potential to fundamentally transform the decision-making process in military operations for both countries. Traditionally, target selection has been a time-consuming process conducted by human analysts, but with the introduction of AI, real-time threat assessment and prioritization will become possible. This will provide a decisive advantage, especially in addressing time-sensitive threats such as ballistic missile attacks from China and North Korea.

However, the realization of this system comes with significant challenges. The United States has requested Japan to strengthen its cybersecurity measures, and the Japanese government is considering using U.S. cloud services to protect the Self-Defense Forces' classified information and promote information sharing with the U.S. This move signifies an increasing dependence on the U.S. in Japan's defense information infrastructure while also bringing strategic benefits in terms of enhancing interoperability between the two countries. However, a delicate policy judgment is required to balance the information management capabilities of a sovereign nation with cooperation with allies.

Discussions on joint missile production are also a key agenda item for this summit. The prolonged war in Ukraine and U.S. airstrikes against Iran have led to a surge in missile demand. Against this backdrop, Japan and the U.S. are seeking to expand cooperation in missile manufacturing, with the Patriot missile being mentioned as a candidate for joint production. Japan is already a major user of the U.S.-made Patriot system, deploying PAC-3 units at six locations: Tokyo, Osaka, Nagoya, Sapporo, Misawa, and Okinawa. Establishing a joint production system not only offers practical benefits such as enhancing supply chain resilience and expanding production capacity but also holds strategic significance in strengthening Japan's defense industrial base.

Furthermore, it is noteworthy that Japan is beginning to deploy its own developed long-range missiles. Reports indicate that glide missiles with a range of several hundred kilometers will be deployed at the Ground Self-Defense Force base in Fuji, Shizuoka Prefecture, while an improved version of the Type 12 surface-to-ship guided missile with a range of over 1,000 kilometers is set to be stationed at other bases. These missiles are a realization of Japan's "counterstrike capability" strategy adopted in 2022. This policy shift, moving from traditional defensive posture to building deterrence that includes offensive capabilities, represents a historic change in Japan's security policy.

Japan has also signed a contract to procure approximately 400 Tomahawk missiles from the U.S. in 2024. These cruise missiles, which are scheduled to be deployed to the Maritime Self-Defense Force, will provide Japan with long-range ground attack capabilities. By combining domestically produced missiles with U.S. systems, Japan is advancing plans to acquire or develop eight types of long-range missiles, aiming to build a multi-layered and flexible counterstrike capability.

However, these developments have also raised new concerns. The U.S. decision to transfer some of the air defense systems deployed in Japan and South Korea to the Middle East to strengthen military involvement in that region has caused anxiety in both countries. Junya Ogawa, the leader of Japan's main opposition party, pointed out in the Diet that U.S. military bases in Japan are permitted for Japan's security and the maintenance of peace in East Asia, not for launching missiles toward the Middle East. The only U.S. aircraft carrier stationed in Japan is currently undergoing maintenance in Yokosuka, raising questions about the U.S. readiness in the Asia-Pacific region.

This situation highlights a fundamental dilemma in the Japan-U.S. alliance. While the U.S. has global security interests, Japan primarily focuses on regional threats. As the situation in the Middle East becomes unstable, the potential withdrawal of U.S. military resources from the Asia-Pacific poses a serious strategic risk for Japan. This underscores the necessity for Japan to enhance its own defense capabilities and justifies the acceleration of building counterstrike capabilities and developing domestic missiles.

The upcoming summit is also expected to discuss the impact of the Middle East situation on security in the Indo-Pacific region. In particular, as China intensifies economic pressure on Japan, both countries are likely to coordinate on cooperation in energy and critical mineral supply chains. This indicates that the alliance is expanding beyond the military domain in an era of deepening interdependence between security and economics.

The evolution of Japan's defense posture should be understood within a broader regional context. Japan is building "quasi-alliance" relationships, such as the Reciprocal Access Agreement (RAA) with Australia and the UK, and promoting a security framework of "Japan-U.S. Plus." These efforts reflect Japan's strategic intent to reduce dependence on a single ally and build a more resilient and diversified security network.

In conclusion, the Japan-U.S. summit on March 19 is likely to mark a new phase in security cooperation between the two countries. The three pillars of an AI-driven target selection system, joint missile production, and expanded information sharing have the potential to qualitatively transform the Japan-U.S. alliance through technological integration and deepening operational interoperability. At the same time, the tension between the U.S.'s global military engagement and Japan's regional security needs highlights the necessity for Japan to strengthen its own defense capabilities and build a more diversified security network. Maintaining this delicate balance while adapting to the changing strategic environment will be a core challenge for Japan's future security policy.