South Korea’s Defense Minister Ahn Gyu-baek acknowledged at the Shangri-La Dialogue in Singapore in June 2026 that Seoul and Tokyo had discussed the possibility of concluding an Acquisition and Cross-Servicing Agreement – a bilateral military logistics pact allowing the armed forces of both countries to provide logistical support during military operations, joint exercises, peacekeeping missions, and humanitarian activities. The ACSA discussion, confirmed by both South Korean and Japanese defense officials on the sidelines of the annual Singapore security forum, represents the most advanced stage yet of the gradual strengthening of South Korea-Japan defense ties driven by shared concern about North Korea’s accelerating ballistic missile program, China’s increasingly assertive military posture, and the uncertainty created by the Trump administration’s intermittent questioning of alliance commitments in the Asia-Pacific. An ACSA between South Korea and Japan would allow the two militaries to share fuel, food, transportation, ammunition, spare parts, and other supplies during joint operations – significantly enhancing bilateral and trilateral cooperation with the United States.

Japan has been the more enthusiastic party in the ACSA discussions, pressing for the agreement as part of a broader push to deepen its defense partnerships in a security environment that Tokyo views as more threatening than at any point since the Cold War ended. Japan’s record defense budget of approximately $58 billion for FY2026 creates the capacity for meaningful logistical cooperation with South Korea, but translating that capability into joint operational arrangements requires precisely the ACSA framework that the Shangri-La discussions advanced. South Korea’s Defense Minister Ahn was notably cautious in his public comments, acknowledging the discussions while emphasizing that “hurdles” must be cleared. Those hurdles include domestic South Korean political resistance to expanding security ties with Japan on grounds rooted in historical grievances over Japan’s 1910-1945 colonial occupation of Korea, and concern that a visible South Korea-Japan defense partnership could damage South Korea’s economic relationship with China, its largest trading partner. The broader Shangri-La Dialogue’s reaffirmation of rules-based order by Indo-Pacific nations provided the diplomatic framing within which Seoul and Tokyo worked to resolve the bilateral obstacles to deeper security cooperation.