Japan, South Korea, U.S. bolster trilateral response to North Korean threats
Felix Kim
Japan, South Korea and the United States are reinvigorating their trilateral security architecture in the face of rising tensions on the Korean Peninsula and broader regional instability.
In late April 2025, the allies conducted a high-level exercise in Seoul followed by the Korea-U.S.-Japan National Defense University Security Policy Forum, also in the South Korean capital. The engagements illustrate the nations’ concerted efforts to fortify deterrence and operational coordination amid evolving strategic uncertainties.
The exercise at South Korea’s National Defense Ministry was the first conducted outside the U.S. since the series began in 2014. The simulation focused on North Korean nuclear and missile threats and was conducted alongside a session of the Defense Trilateral Talks, the nations’ vice-ministerial security dialogue mechanism.
The exercise’s resumption after a five-year hiatus reflects a growing urgency to revitalize coordination.
“You can’t prepare for everything, but if you don’t exercise and develop strategic concepts together, you’ll have gaps,” Dr. Bruce Bennett, a Northeast Asia defense expert at the Rand Corp., told FORUM. “The growing nuclear threat demands coordinated action.
“I think there’s now a recognition that if you want to prepare to deal with China, you need your allies with you,” he said. “That means doing tabletop and field exercises together to identify threats, formulate responses and synchronize strategic thinking.”
The Security Policy Forum brought together defense scholars and policy experts from each country to address the theme “Changes in the International Situation and Korea-U.S.-Japan Security Cooperation.” In his keynote address, National Defense University President Lim Ki-hoon noted the regularization of trilateral academic forums to “systematize and sustain cooperation.”
Participants analyzed the threat environment on the Korean Peninsula and discussed how to overcome obstacles to deeper defense integration.
In early April, the nations’ foreign ministers met in Brussels, Belgium, and reaffirmed their commitment to strengthening deterrence. In a joint statement, Japanese Foreign Minister Takeshi Iwaya, South Korean Foreign Minister Cho Tae-yul and U.S. Secretary of State Marco Rubio emphasized the critical role of U.S. extended deterrence, condemned North Korea’s military ties with Russia, and called for a firm response to Pyongyang’s cyberattacks and missile threats.
The leaders “strongly opposed unlawful maritime claims or any unilateral attempts to change the status quo by force or coercion in the waters of the Indo-Pacific, including the South China Sea.”
Japan and South Korea also “reaffirmed their commitment to bolstering defense and deterrence by advancing robust security cooperation and strengthening their respective defense capabilities,” the statement said.
Felix Kim is a FORUM contributor reporting from Seoul, South Korea.
