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Korea-U.S. alliance faces new strains — time to revisit lessons from past conflicts

Published: 13 Jun. 2025, 00:04

Yun Byung-se

The author is the co-chair of GC REAIM and a former foreign minister.

President Lee Jae-myung’s participation in the Group of 7 (G7) summit in Canada from June 15 to 17 is a diplomatic milestone. As part of his administration’s goal to join a “G7 Plus” framework, the summit offers a valuable chance to solidify Korea’s presence in global governance. If President Lee also attends the NATO summit later this month, it will mark a confident debut on the international stage and set the tone for Korea’s successful hosting of the APEC summit in Gyeongju this fall.

What gives this G7 meeting even greater weight is the presence of U.S. President Donald Trump, who has historically taken a critical stance on both G7 and NATO. It will provide an opportunity for Korea to engage in trilateral and bilateral summits with the United States and Japan. More importantly, it could allow the three countries to build personal trust among leaders and manage issues such as tariffs and regional security in a more stable and constructive manner.

The world is now facing a compounded crisis, made more uncertain by the return of the Trump administration. This moment could mark a systemic shift in the international order that has underpinned global stability for over 80 years. For Korea, how it navigates the evolving scope and role of its alliance with the United States will be a defining test for the new administration, not just over its five-year term but for the nation's long-term security and prosperity.

From left: U.S. Defense Secretary Pete Hegseth, Australian Deputy Prime Minister and Minister for Defence Richard Marles, Japanese Minister of Defense Nakatani Gen and Philippine Secretary of National Defense Gilberto Teodoro Jr. pose for photos following their multilateral meeting on the sidelines of the International Institute for Strategic Studies' Shangri-La Dialogue Defence Summit in Singapore on May 31. [EPA/YONHAP]

Compared to the U.S. global posture review (GPR) under President George W. Bush — which sparked tension with Seoul during the Roh Moo-hyun administration — today's alliance challenges are more widespread, complex and urgent.

The Trump administration now identifies China as the sole pacing threat, relegating North Korea’s nuclear ambitions to a lower priority. As U.S. Secretary of Defense Pete Hegseth emphasized during his address at the Shangri-La Dialogue last month, Washington has made its strategic pivot toward countering China official. The United States is recalibrating the expectations it has of allies, asking them to bear greater burdens, including risk exposure. Japan, Australia and the Philippines have signaled support for this new direction, often referred to as the “Squad.” Korea is now under increasing pressure to align with this vision.

The Lee administration faces three core dilemmas.

A security gate and fence outside the site of the Group of 7 Leaders meeting that takes place from June 15 to 17, is pictured in Kananaskis, Alberta, on June 2. [AP/YONHAP]

First, the issue of U.S. Forces Korea’s “strategic flexibility” needs new terms of coordination. If disagreements persist, Korea could face a renewed debate over troop reductions, the early transfer of wartime operational control (Opcon), changes in the roles of U.S. and UN commands in Korea and Japan and pressure to increase its defense spending significantly.

The last time this issue surfaced was in 2003, when the United States sent a brigade from Korea to Iraq and requested that Korea dispatch additional troops. That period also saw a cut of 12,500 U.S. troops and plans for the Opcon transfer. The 2006 agreement between Seoul and Washington managed to defuse tensions with a clause affirming that Korea would not be drawn into conflicts in Northeast Asia, including over Taiwan, without its consent. Today, however, Washington’s concept of strategic flexibility involves using Korea as a potential staging ground — similar to Japan or the Philippines — regardless of prior consultations. If Korea pushes for a pre-coordination clause, the United States may simply redeploy troops elsewhere, potentially triggering further reductions in ground forces on the peninsula.

Second, Seoul must define the scale and scope of Korea’s regional security role. With the Taiwan Strait, East China Sea, South China Sea and West Sea increasingly interconnected in the U.S. Indo-Pacific strategy, Korea will likely be asked to clarify how far it is willing to go militarily. Recent trilateral summit statements, including the 2023 Camp David declaration, have already pushed Korea’s position toward deeper engagement. The Trump administration will be watching to see whether Seoul stays the course.

Third, Seoul must prepare for the possibility that the United States could officially define China — a country with which Korea maintains a strategic partnership — as a hostile actor within the alliance framework. In the early 2000s, U.S.-Korea military leaders abandoned a joint threat assessment after failing to agree on whether to label China a threat. But Trump’s team is pushing allies to adopt unambiguous positions. Hegseth’s speech, which focused heavily on Taiwan, reflects a much more forceful demand than during Bush’s GPR era.

The continued ambiguity from Washington on whether it will maintain extended deterrence on the Korean Peninsula — while placing priority on a Taiwan contingency — raises concerns about a possible security vacuum. It also revives questions over the scope and conditions under which the U.S.-Korea Mutual Defense Treaty would be activated. A recent Taiwan-Korea dual contingency nuclear war game hosted by the Atlantic Council, with extensive participation from U.S. military officials, underscores the gravity of this scenario.

U.S. Forces Korea helicopters are seen at Camp Humphreys in Pyeongtaek, Gyeonggi, on April 9. [YONHAP]

Past U.S.-Korea administrations — Roh-Bush and Moon-Trump — experienced sustained alliance friction due to early-term policy clashes. Trump’s second term already shows signs of unilateralism that may strain ties with allies. Elbridge Colby, a former Pentagon official and key architect of Washington's anti-China strategy, wrote in his book “The Strategy of Denial” (2021) that while Japan and Australia should clearly be part of the U.S. defense perimeter, it is not self-evident that other countries should be.

In this increasingly fraught security environment, the new Korean government must work early to establish mutual trust with Washington. Only by proving that Korea is an indispensable ally can it protect its national interests amid rising pressure and uncertainty.

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.