Concerns are mounting in South Korea over the evolving role of the United States Forces Korea (USFK) after a “secret” Pentagon memo directed the unit to prioritize “deterring China’s seizure of Taiwan” and “strengthening homeland defense” even at the cost of “assuming risks” in other regions.
The apparent new Pentagon policy could shift the primary mission of the 28,500 American troops stationed in South Korea from deterring North Korea to countering China—a move that, for Seoul, risks creating a security vacuum and straining already delicate relations with Beijing.
According to a March 29 Washington Post report, US Defense Secretary Pete Hegseth distributed a classified document titled “Interim National Defense Strategic Guidance” across the US Defense Department in mid-March.
The document reportedly outlines US President Donald Trump’s vision for preparing for and potentially winning a conflict against China while also defending US interests in the “near abroad” region, including Greenland and the Panama Canal.
The document, reportedly signed by Hegseth, aims to restructure America’s Indo-Pacific military initiatives, shifting focus away from North Korean threats to China’s potential aggression against Taiwan.
The shift comes despite North Korea’s recent provocations, including the development and brandishing of new long-range missiles capable of hitting the US mainland.
To address shortages in personnel and resources, the document states that the Pentagon “will assume risk in other theaters,” thereby pressuring allies in Europe, the Middle East and East Asia—including South Korea—to take on greater deterrence roles against regional adversaries such as Russia, Iran and North Korea.
This reflects a broader burden-sharing strategy that has defined Trump’s foreign policy since his first term. The shift could potentially increase South Korea’s defense spending, as the country reshapes it defense strategy to be less reliant on the permanent presence of US troops.
It’s unclear if the memo’s “other theaters” means the US is considering a new policy of basing American troops in Taiwan and perhaps moving them out of South Korea.
“[South Korea] says it respects USFK’s ‘Strategic Flexibility,’ but that is all just empty words. [South Korea] needs the USFK anchored on the peninsula,” said Lee Sang-soo, a visiting research fellow at the Jeju Peace Institute, in an interview with Asia Times.
Under North Korea’s nuclear threat, Seoul lacks the capability to contain its neighbor without US troops, according to Lee. This makes the USFK’s presence on the peninsula crucial for South Korea’s security, he said.
Redeployment risks
The idea of expanding the USFK’s role in the Indo-Pacific is not new.
In 2006, then-South Korean Foreign Minister Ban Ki-moon—who later became the UN’s Secretary-General—and former US Secretary of State Condoleezza Rice first agreed on the concept of “Strategic Flexibility,” allowing for possible USFK deployments beyond the Korean Peninsula.
However, the US has historically recognized Seoul’s need for a constant security guarantee, embodied by the American troops who have remained in South Korea since the Korean War.
Now, concerns are growing that the Pentagon’s new guidance makes the USFK’s redeployment a realistic possibility.
“A security vacuum created by the USFK’s departure could lead North Korean leader Kim Jong Un to miscalculate,” said Kang Joon-young, a professor at Hankuk University of Foreign Studies, in an interview with Money Today.
A reduced USFK presence could also be used as leverage by Washington in defense-cost negotiations, with the US potentially demanding greater financial contributions from Seoul.
“The US has consistently urged South Korea to contribute more to maintaining the USFK,” said Lee, the researcher. “It could also resort to economic pressure, such as tariffs, to extract what it considers a fair share for stationing troops.”
Lee’s concerns are now reality. On April 2, Trump unveiled his long-anticipated list of “reciprocal tariffs” to offset the “unfair” trade practices of countries that export to the US. South Korea was slapped with a new 26% tariff.
South Korea was given a special shout-out during Trump’s joint address to Congress on March 5 that outlined his logic behind reciprocal tariffs.
“South Korea’s average tariff is four times higher… And we give so much help militarily and in so many other ways to South Korea, but that’s what happens,” Trump said in the address, labeling South Korea as a country that unfairly treats the US.
Trump’s remarks, which associate tariffs with military aid, have sparked concerns in South Korea that the US could increase its tariffs further when defense-cost negotiations begin.
“Trump is trying to adopt a methodology where he links trade issues with security ones,” said Kim Dae-shik, floor spokesperson of South Korea’s ruling People’s Power Party.
“In the defense cost-sharing negotiations, South Korea needs a strategy that maintains a principled stance while also blocking any linkage to trade negotiations,” Kim added.
South Korea has already agreed to increase its annual defense contributions to US$1.3 billion by 2026, after which costs will increase annually based on South Korea’s Consumer Price Index.
However, Trump suggested on the campaign trail that he would demand as much as $10 billion annually from Seoul.
Taiwan dilemma
The Trump administration may also pressure South Korea to assume a more active role in Taiwan’s defense, said Andrew Yeo, a senior fellow at the Brookings Institution, a Washington-based think tank.
To be sure, US pressure on South Korea to clarify its stance on Taiwan is not new. Seoul’s reluctance to define its role in a Taiwan contingency involving Chinese aggression stems from its focus on North Korean threats and its economic dependence on Beijing.
However, the Trump administration may push South Korea into “more concrete discussions related to Taiwan,” according to Yeo.
“The United States may push South Koreans outside of their comfort zone to provide more clarity and pledge robust support for the US-South Korea alliance in the event of a Taiwan Strait contingency,” Yeo wrote in a recent report.
Lee noted that if China invades Taiwan, the US may require South Korea to make high-risk commitments, such as deploying South Korean troops to Taiwan, permitting US forces to use South Korean air and naval bases, or assisting in logistics and reconnaissance operations.
Any overt South Korean commitments to Taiwan’s defense would inevitably strain economic relations with Beijing. China is South Korea’s largest trading partner, with exports to China reaching $133 billion in 2024, up 6.6% year on year.
Given South Korea’s export-oriented economy, China’s market will become all the more important in the wake of Trump’s new prohibitive tariffs.
“This will be a difficult balancing act, but South Korea must align its position on Taiwan closely with that of the United Nations. It must support Beijing’s ‘One China’ policy, while doing its full duty as an ally of the US,” Lee added. “[South Korea] needs to take into account its economic ties with China.”
China has reacted strongly when South Korea has previously deepened its strategic alignment with the US.
For example, when Seoul deployed the THAAD missile defense system in 2016, Beijing saw it as a threat and imposed unofficial economic sanctions, including a tourism ban, trade restrictions and consumer boycotts that cost South Korea billions in losses.
Geopolitical gamble
Despite these concerns, the South Korean government claims it is still confident in America’s commitment to deterring North Korea.
“There has been no official statement or confirmation from the US Department of Defense,” South Korea’s Defense Ministry stated a day after the Washington Post report on the secret memo was released.
“The peace and stability of the Korean Peninsula remain the USFK’s primary function, and that has not changed,” it said.
But as Washington reshapes its Indo-Pacific strategy, Seoul faces mounting pressure to align with emerging new US priorities while balancing its own security and economic interests.
Whether South Korea can maintain strategic autonomy or will be drawn deeper into great-power competition remains uncertain, especially amid ongoing political turmoil and the impending economic impact of Trump’s new tariffs.
With Pyongyang watching closely and Beijing poised to retaliate, the choices Seoul makes in the coming months could redefine its geopolitical standing and risks for years to come.
