The proposal from a recent think tank report from Washington to reduce the U.S. troops’ presence in South Korea opens the door for a reflection on the changing geopolitics of the Korean Peninsula amid the unprecedented economic and political disruptions being unleashed by US President Donald Trump in his second term.
Defense Priorities, a Washington-based think tank, released a report in July titled “Aligning Global Military Posture with U.S. Interests,” which called for a comprehensive review of the U.S. troop presence abroad in light of changing American interests. In the Korean Peninsula, it calls for a reduction in the U.S. Forces Korea (USFK) troop level to about 10,000 from the current 28,500.
Prioritizing China over Korea
The report argues that the “U.S. presence should be reduced further…especially if South Korea continues to limit the U.S. ability to use defence assets in Korea to address other regional security crises.” It reflects Washington’s concerns over Seoul’s historical resistance to using the U.S. military assets on its soil, especially for serving broader interests such as containing China. For instance, after the U.S. deployed the Terminal High Altitude Area Defense (THAAD) missile system, South Korea faced Chinese economic retaliation and its liberal government adopted the “Three Noes”, which included no additional THAAD batteries, no participation in the U.S.-led regional missile defense system, and no trilateral military alliances with the U.S. and Japan. The justification for the downsizing is the perceived urgency of reorganizing the U.S. military posture in the region to address the mounting threat from China.
South Koreans, however, see the U.S. troops as the bulwark against the threat from North Korea, and are wary of getting drawn into U.S. security activity elsewhere in the region, especially of being sucked into the U.S.-China regional conflict in Asia. Yet, this is not the first time that the U.S. has reduced troops in South Korea. In 1960, the Eisenhower administration reduced the number of troops to 55,000. A more significant reduction occurred in 1971, when the Nixon administration withdrew the 7th Infantry Division as part of the Nixon Doctrine, emphasizing greater self-reliance among U.S. allies.
The presence of U.S. troops in the Korean Peninsula has long been an enduring feature of North East Asian security. With some 28,500 American soldiers stationed in South Korea, the alliance has survived Cold War tensions and the post-Cold War evolution of the North East Asian security landscape. It is becoming less clear if the structure of the U.S. military presence and the alliance between Washington and Seoul will remain unchanged as the U.S. redefines its strategic priorities and President Donald Trump seeks a radical overhaul of US alliances and security commitments.
The essence of the new argument that has gained ground in the Second Trump Administration has been articulated by Elbridge Colby, currently the Under Secretary of Defense Policy in the US Department of Defense. In May 2024, Colby had argued that “The fundamental fact is that North Korea is not a primary threat to the U.S.” He insisted, therefore, that “South Korea is going to have to take primary, essentially overwhelming responsibility for its own self-defense against North Korea because [the U.S. doesn’t] have a military that can fight North Korea and then be ready to fight China.” That South Korea has a significant military strength and is a rich nation reinforces this argument, especially among sections of President Trump’s political coalition that are calling for greater burden-sharing between the U.S. and its allies in Europe and Asia.
From Burden Sharing to ‘America First’
This view, articulated during the first term of President Trump, involved him repeatedly questioning the costs of overseas deployments in general and demanding that allies, including Seoul, pay substantially more for the U.S. military presence. The resulting cost-sharing negotiations became a flashpoint, with Trump even suggesting troop reductions as leverage. Unlike in the first term, when Trump was constrained by the traditional conservatives in his administration, in the second term, he has much greater room to pursue his convictions on “America First” and its logical extension to security alliances.
The report from Defense Priorities on force reduction closely reflects the America First sentiments and is bound to be taken seriously in the Korean Peninsula, Japan, and China. Traditionalists in Washington and Seoul are strongly opposed to the force reductions, believing they would undermine regional security. They also opposed Trump’s attempts to make peace with the North Korean leader Kim Jong-Un in the first term. Trump was the first US president to set foot on North Korean soil. Between 2018 and 2019, Trump met Kim Jong-Un three times to discuss denuclearization. Although his peace initiative failed, Trump has not given up on the idea and is likely to take it up at some point in his second term.
The voice of the traditional internationalists in Washington has weakened under Trump. In South Korea, the progressives have long resented the presence of large U.S. forces in their country and are more open to peace and reconciliation with North Korea and finding common regional security ground with China. The recent election of the left-leaning Lee Jae-Myung as president of South Korea could create an interesting diplomatic space for rethinking security on the Korean Peninsula.
Optimists bet that Trump’s America First policies do create space for the progressives led by President Lee to explore the rearrangement of the security order in the Korean Peninsula. After his election, Lee reaffirmed his commitment to reengage North Korea while continuing to work closely with the U.S. and Japan.
Seoul’s Choices and Their Implications
President Lee could propose scaling back joint military exercises and U.S. strategic asset deployments to the Korean Peninsula. In the past, such measures were implemented by the alliance, and since Trump had criticised them as being expensive, cutting back on them might appeal to both President Lee and him. Kim Jong-Un had always called this joint activity offensive and unacceptable.
Many on the South Korean left have long sought greater control over their own armed forces and full sovereign rights in dealing with their neighbours. They may seek the transfer of wartime operational military control (OPCON) from the U.S., an issue that has been a key factor in the Lee administration’s broader defense goals. While South Korea maintains command authority in peacetime, wartime control authority remains under the U.S.-led Combined Forces (CFS), currently headed by a U.S. general. Government officials believe that the OPCON issue “could serve as leverage in defence cost-sharing negotiations” and in response to U.S.’s pressure for South Korea to support a broader regional role for American forces. This could well suit the restrainers in the U.S.
But radical departures from the congealed security order in the Korean Peninsula are not easy. It is by no means clear if Lee can build a domestic consensus around a new approach to stabilising relations with North Korea. Trump is not known for patience and might not be able to devote sustained attention to the Korean question that has vexed the region since the Second World War. China and Japan will have concerns of their own about major changes in the military equations of the Korean Peninsula. Meanwhile, North Korea remains as unpredictable as ever. The rest of Asia, including India, would carefully watch to see how Trump’s ‘America First’ policy intersects with the domestic politics in South Korea, the intra-Korean dynamic, and regional geopolitics.