Collaboration among Japan, South Korea and the United States is crucial for stability and security in the Indo-Pacific region, policy experts said at a recent event to discuss the three nations’ diplomatic relations.
“Our most important mission … in our diplomacy, is to take the necessary steps to bring Japan and [South Korea] closer, ever closer together,” Kurt Campbell, former U.S. deputy secretary of state and chairman of The Asia Group, a Washington D.C.-based consulting firm, said during a conference hosted by the Center for Strategic and International Studies (CSIS). “What is remarkable is that in fact, behind the scenes, the amount of trilateral engagement has increased rather substantially.”
The June 2025 conference, held in Washington, D.C., marked the 60th anniversary of diplomatic relations between Japan and South Korea. It also took place against the backdrop of rising tensions in the region with aggression from China and North Korea and increasing cooperation among China, Iran, North Korea and Russia.
Campbell noted that expanding collaboration to enhance security will require the Partners to be more transparent in sharing intelligence and technology. “We’ve got to work more constructively in these partnerships in ways that, frankly, are occasionally bureaucratically resisted,” he said. “The goal here would be to work with other like-minded states in the Indo-Pacific — this is the core three — if we can get this right, then much of our challenge in the Indo-Pacific has been addressed.
Japan and South Korea both have sought to work more closely with the U.S. on security issues as tensions in the region increase. Seoul and Tokyo have boosted their profile on the international scene. In June 2025, defense officials from Australia, Japan and South Korea held their first trilateral meeting on the sidelines of the Asia Security Summit, also called the Shangri-La Dialogue, in Singapore, The Korea Post newspaper reported.
Japan, the Republic of Korea and the U.S. held combined air drills in mid-June 2025 to strengthen their trilateral security cooperation against North Korean threats, Yonhap News Agency reported. And Exercise Freedom Edge, conducted in November 2024, included exercises across land and sea domains.
These exercises came out of a 2023 summit with the three nations at Camp David in Maryland aimed at deepening relations and addressing geopolitical threats. That period “was characterized by an increasingly aggressive, increasingly forward-leaning Beijing that pressured both Korea and Japan on multiple fronts,” said Adam Farrar, senior geoeconomics analyst for Asia-Pacific at CSIS. Those pressures included China “leveraging its massive economic power for coercion,” he said.
“The idea that China on a whim can turn off billions of dollars of economic aid, stop the flow of cultural content and pressure a government to make national security decisions based on its own priorities force the administrations in Korea and Japan to think about how they could better posture themselves to defend against that.” He also noted that China is building infrastructure outside of its sovereign waters.
In addition to China’s aggression, North Korea has increased its threats and weapons buildup, working more closely with Russia and sending North Korean troops to fight in Ukraine, Farrar said.
“What is Russia giving North Korea? What will that mean for North Korea’s ability to threaten the region or its willingness to return to negotiations?” Farrar said. “Every single one of these dynamics has helped transition the mentality of leaders in each of these capitals to recognize there is a deep need to engage and find ways to push back and demonstrate strength and deterrence against these threats.”