Korea must join U.S. in decoupling from China, but stay open to China, Russia and North Korea

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Korea must join U.S. in decoupling from China, but stay open to China, Russia and North Korea

Published: 18 Jun. 2025, 00:03 Updated: 18 Jun. 2025, 09:36

Audio report: written by reporters, read by AI

Lee Sang-hyun

The author is a senior research fellow at the Sejong Institute

As the Trump administration begins its second term, it is clear that changes to the size and role of U.S. Forces Korea (USFK) — currently about 28,500 strong — are being considered. Several signs point in this direction. In May, the Wall Street Journal, citing U.S. Defense Department officials, reported that about 4,500 U.S. troops — likely the Stryker brigade — are being considered for relocation to other regions. The Stryker brigade, equipped with wheeled armored vehicles, began rotational deployment to South Korea in 2022 to improve rapid response capabilities.

U.S. Army General Xavier Brunson, the new commander of USFK, highlighted the strategic value of U.S. forces in Korea during an American Army Association symposium in Hawaii last May. He described Korea as “like an island or a fixed aircraft carrier” between Japan and mainland China — hinting at a role for USFK beyond the Korean Peninsula.

President Lee Jae Myung speaks to reporters at a press briefing on a presidential flight en route to the Group of Seven (G7) summit in Canada on June 16. [JOINT PRESS CORPS]

Meanwhile, the United States and Japan are discussing a “One Theater” concept that would treat the Korean Peninsula, East China Sea and South China Sea as a single battlefield. This approach aims to strengthen defense cooperation among the United States, Japan, Australia, the Philippines and possibly South Korea to balance China's influence.

If realized, this concept could shift USFK’s mission sharply toward countering China, rather than deterring North Korea. The Trump administration, which is preparing for significant pay increases from countries under its security umbrella, may demand higher cost-sharing from Korea. While increasing Korea’s defense budget may be manageable, a shift in the role and posture of USFK presents a more complex challenge.

Elbridge Colby, U.S. defense policy undersecretary and an architect of the new U.S. National Defense Strategy, is known as a “prioritiser.” He advocates focusing U.S. forces on China while urging allies to assume greater responsibility for their own security. For Korea, caught between Washington and Beijing, maintaining strategic flexibility will be essential.

U.S. soldiers salute during a change-of-command ceremony for the United Nations Command, Combined Forces Command and the United States Forces Korea (USFK) at Camp Humphreys in Pyeongtaek, Gyeonggi, on Dec. 20, 2024. [AP/YONHAP]

Several scenarios are now plausible: reducing USFK, partial withdrawal or repurposing Korean-based troops for China-related contingencies. Victor Cha, Korean chair at the Center for Strategic and International Studies, warns that President Trump could leverage USFK as a negotiation tool and may even threaten full withdrawal if Korea resists U.S. demands .

These debates revive memories of similar discussions under the Roh Moo-hyun administration. At that time, Korea agreed to U.S. strategic flexibility — allowing U.S. deployment in broader Northeast Asia — but secured an agreement that U.S. forces would not engage in regional crises without Korean consent.

Looking ahead, if the Trump administration seeks to deploy USFK for operations beyond the peninsula — especially relating to China-Taiwan issues — Seoul must clarify its response.

The mutual defense treaty (Article 3) ties U.S. forces to the Pacific region. If U.S. troops are stationed nearby, strategic flexibility may be legally and operationally justified. Seoul should prepare for the possibility of security gaps if land forces are retasked, since USFK primarily comprises ground troops.

Given the Trump administration’s shift, Korea must support the United States in its push to contain China, while ensuring it does not weaken national security. Korea should offset U.S. military resource limitations by stepping up its own contributions.

The key question is whether Korea will actively participate in the U.S.-China strategic rivalry — and how deeply. President Lee Jae Myung has signaled openness to forging closer ties with China. Since China remains a crucial trade partner, closer engagement seems inevitable. But if the United States perceives Seoul as undermining its China policy, the partnership could suffer.

After the June 3 election, the White House described the vote as “free and fair,” while also expressing concern about Beijing’s interference in global democracies. That statement should be read in context.

The Lee administration faces a delicate balancing act: supporting United States' China deterrence while resisting excessive American demands. President Lee has stressed that no better security framework exists than the U.S.-Korea alliance. His support for the alliance is practical, not ideological.

A general view during a meeting of NATO Ministers of Foreign Affairs, at the NATO headquarters, in Brussels, Belgium, 03 April 2025. [EPA/YONHAP]

For such pragmatic diplomacy to work, Seoul must also display openness to engage with China, Russia and North Korea. That will mark a break from the value-driven foreign policy seen under the Yoon Suk Yeol administration, though it risks being seen as opportunistic if not clearly principled.

President Lee's first diplomatic challenges await. After a June 6 telephone call with President Trump, he attended the G7 summit in Canada — an opportunity to allay concerns and demonstrate the sincerity of his pragmatic approach. If he attends the NATO summit in the Netherlands on June 24 to 25, it will be the first true test of Lee Jae Myung–style pragmatic diplomacy.

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