Japan-South Korea Defense Cooperation: Historic Resumption of Joint Exercises and AI Collaboration

On January 30, 2026, Japanese Defense Minister Shinjiro Koizumi and South Korean Defense Minister Ahn Gyu-back met in Seoul and reached a historic agreement to significantly strengthen bilateral defense cooperation. This comprehensive agreement includes the resumption of naval search and rescue (SAR) exercises, suspended since 2017, and the establishment of a new framework for cooperation in artificial intelligence (AI) and unmanned weapon systems.

According to the joint press statement, both nations agreed that stable promotion of defense cooperation and exchanges is crucial. They committed to annual mutual visits and defense ministerial meetings, institutionalizing high-level dialogue that had been stagnant since 2015.

The resumption of SAR exercises carries strategic significance beyond humanitarian cooperation. Since the December 20, 2017 radar lock-on incident between a South Korean destroyer and a Japanese P-1 maritime patrol aircraft, bilateral maritime cooperation had been effectively frozen for nine years. However, with North Korea's ballistic missile launches becoming routine, including a hypersonic missile test into the Sea of Japan on January 5, 2026, both nations recognized the necessity of practical cooperation.

Japan's Ministry of Defense plans to deploy new anti-ship guided missiles with a range of approximately 1,000 kilometers to the Ground Self-Defense Force's 5th Surface-to-Ship Missile Regiment in fiscal year 2026. The deployment location at Camp Kengun in Kumamoto Prefecture, Kyushu, facing the East China Sea, suggests preparation for Taiwan Strait contingencies.

Meanwhile, South Korea is advancing rapidly in unmanned and AI systems. The ROK Army has begun operational deployment of the unmanned K-CEV combat engineering vehicle under the TIGER Plus modernization program. This system integrates AI weapon stations, drones, and explosive ordnance disposal robots.

The explicit mention of AI and unmanned weapon systems cooperation in the Japan-ROK agreement indicates both nations intend to jointly enhance capabilities while ensuring interoperability. This holds significant implications for the trilateral security cooperation framework involving the United States.

However, this defense cooperation progress has drawn criticism from North Korea. On January 13, 2026, North Korean state media condemned Japan's launch of a new attack submarine, mass production of new anti-ship missiles, and recent defense buildup as a "revival of past militarism."

China also remains wary of Japan-ROK rapprochement. Activities by the China Coast Guard and People's Liberation Army Navy in the East China Sea and Sea of Japan have increased in recent years, with intrusions into waters around the Senkaku Islands continuing into 2026.

The institutionalization of Japan-ROK defense cooperation will have long-term impacts on regional security architecture. By institutionalizing annual defense ministerial meetings and strengthening communication between defense authorities, both nations can reduce risks of misunderstanding or accidental conflict in contingencies.

The January 30, 2026 Japan-ROK defense cooperation agreement represents a crucial turning point in Northeast Asian security. Facing the triple challenges of North Korea's nuclear and missile threats, China's maritime expansion, and Russian military provocations, the institutionalization of substantive defense cooperation between Japan and South Korea is an indispensable step toward regional stability.