The Deployment of Japan's Long-Range Missiles Indicates a Turning Point in Northeast Asia's Defense Posture

In March 2026, Japan is set to reach a significant milestone in its defense policy. The Japan Ground Self-Defense Force's 5th Anti-Ship Missile Regiment is preparing to deploy the improved Type 12 surface-to-ship guided missile at the Kumamoto Prefecture Kengun garrison, with operational commencement approaching a year earlier than initially planned. This deployment symbolizes a fundamental shift in Japan's defense strategy, going beyond mere equipment updates.

The improved Type 12 surface-to-ship guided missile has significantly extended its range from the conventional 200 kilometers to approximately 1,000 kilometers, acquiring the capability to cover a vast maritime area from the East China Sea to the Japan Sea. The Ministry of Defense has allocated about $1.13 billion (approximately 170 billion yen) in the fiscal 2026 budget for the procurement of this improved missile system, positioning it as Japan's first domestically produced long-range missile. Following the deployment in Kumamoto Prefecture, there are plans to expand to the Fuji garrison of the Japan Ground Self-Defense Force in Shizuoka Prefecture in fiscal 2027, gradually enhancing anti-ship attack capabilities from the southwestern to the eastern regions of the Japanese archipelago.

This acceleration of the deployment schedule reflects the rapid changes in the security environment in Northeast Asia. China's maritime expansion, rising tensions in the Taiwan Strait, and North Korea's continued ballistic missile launches have instilled a sense of urgency among Japan's defense planners. In his New Year remarks in January 2026, Maritime Self-Defense Force Chief Admiral Akira Saito pointed out, "China's maritime expansion and tensions in the Taiwan Strait and South China Sea, Russia's invasion of Ukraine, and North Korea's ballistic missile launches continue to threaten the international order, and threats in cyberspace and outer space are also increasing," emphasizing the growing importance of the Maritime Self-Defense Force's role.

The deployment of the Type 12 missile is part of the realization of the national security strategy formulated by Japan in December 2022. This strategy explicitly states the possession of "counterstrike capabilities," while maintaining the traditional framework of exclusively defensive posture, it has called for the strengthening of deterrence, including the capability to attack enemy bases. Prime Minister Sanae Takaichi has expressed the intention to revise the national security strategy, defense strategy, and defense capability development plan ahead of schedule within 2026, accelerating the review of defense posture. The defense budget for fiscal 2026 is set to record a historic high of 9 trillion yen (approximately $58 billion), an increase of 3.8% from the previous year. This level reaches 2% of Japan's GDP, indicating an expansion of defense investment in line with NATO standards.

Japan's strengthening of defense capabilities is also linked to deepening defense cooperation with South Korea. On January 30, 2026, Defense Minister Shinjiro Koizumi and South Korean Defense Minister An Gye-berk met at the Yokosuka base in Kanagawa Prefecture and agreed to elevate defense cooperation. The two countries agreed to begin discussions on the joint development and operation of artificial intelligence (AI) and unmanned weapon systems, aiming to deepen collaboration in the technology sector. Furthermore, it is noteworthy that they agreed to resume humanitarian search and rescue training (SARE) between the Japan Maritime Self-Defense Force and the South Korean Navy for the first time in nine years.

This resumption of training symbolizes the normalization of Japan-South Korea defense exchanges, which had been interrupted by the radar illumination issue that occurred in December 2018. The two defense ministers confirmed their commitment to "activate personnel exchanges and unit exchanges to enhance mutual understanding and trust between the Self-Defense Forces and the South Korean military," and agreed to maintain a framework for regular defense ministerial meetings. In January, various multi-layered exchange programs were conducted, including exchanges between students from the Japan Ground Self-Defense Force's Officer Candidate School and students from the South Korean Army's three military academies, the first port call of the South Korean Air Force's Black Eagles at the Japan Air Self-Defense Force's Naha base, and exchanges with the Japan Air Self-Defense Force's Blue Impulse, advancing the substance of defense cooperation.

The strengthening of Japan-South Korea defense cooperation is positioned within the framework of trilateral security cooperation among Japan, the United States, and South Korea. At the Japan-U.S.-South Korea defense ministerial meeting held in Tokyo in July 2024, it was decided to conduct regular joint training called "Freedom Edge," which will institutionalize integrated training across multiple domains, including maritime, air, cyber, and space. This framework focuses on addressing North Korea's nuclear and missile threats and deterring China's maritime expansion, indicating the strengthening of the U.S. alliance network in Northeast Asia.

However, there are structural challenges to deepening Japan-South Korea cooperation. At the Japan-South Korea summit held in Nara on January 13, 2026, Prime Minister Takaichi and President Lee Jae-myung confirmed their collaboration on economic security and the denuclearization of the Korean Peninsula, but historical recognition issues remain a potential risk factor in bilateral relations. The two leaders agreed to advance DNA testing of remains related to the 1942 Chosei coal mine accident, but this remains "a small yet meaningful progress on past issues" (President Lee) and has not led to fundamental historical reconciliation.

The new National Defense Strategy (NDS) announced by the Trump administration in January 2026 compels a redefinition of alliance relationships in Northeast Asia. While prioritizing deterrence against China, the strategy clearly indicates a demand for greater defense burdens from allied nations. In this context, Japan's strengthening of defense capabilities and the deepening of Japan-South Korea cooperation serve to respond to U.S. strategic demands while also providing an opportunity for both countries to enhance their autonomous defense capabilities.

Kumamoto, the deployment site of the Type 12 missile, occupies a geopolitically important position. Located in the southwestern part of Kyushu, Kumamoto allows access to the Japan Sea via the East China Sea and the Tsushima Strait, enabling coverage of the maritime area through which Chinese naval vessels pass when advancing into the Pacific. According to Ministry of Defense officials, this deployment is positioned as "part of the defense of the southwestern islands," but it is expected to function effectively as a deterrent against China's maritime activities.

Japan's shift in defense posture is bound to affect the regional military balance. The Chinese Ministry of National Defense has criticized Japan's strengthening of defense capabilities as "an act that heightens regional tensions," deepening strategic mutual distrust between Japan and China. At the same time, North Korea has condemned the strengthening of Japan-U.S.-South Korea cooperation as a "hostile military alliance," using it as a justification for enhancing its nuclear capabilities. The security dilemma in Northeast Asia is creating a vicious cycle in which the strengthening of defense capabilities by each country reacts to one another.

In this situation, Japan's defense policymakers are faced with the challenging task of balancing the enhancement of deterrence with diplomatic stability. The deployment of the Type 12 missile technically means the capability to target military facilities in China and North Korea, but politically, it carries the risk of accelerating the regional arms race. The Japanese government maintains its position that "the principle of exclusively defensive posture will be upheld," but there are questions about how the possession of long-range strike capabilities aligns with this principle, raising accountability domestically and internationally.

The commencement of the Type 12 missile deployment in March 2026 is likely to become a symbolic event in Japan's defense history. It marks the moment when Japan will first deploy a full-fledged long-range strike capability in a practical sense since the end of the Cold War, indicating that the security environment in Northeast Asia is entering a new phase. As the deepening of the Japan-U.S. alliance, the expansion of Japan-South Korea cooperation, and the qualitative transformation of Japan's own defense capabilities progress simultaneously, the strategic challenge of how to maintain peace and stability in the region will undoubtedly remain a central theme in Japan's diplomatic and security policy for the coming years.