United States Forces Korea (USFK), established in 1957, maintains deterrence and strengthens the US-South Korea alliance on the Korean Peninsula.
Through continuous training, intelligence sharing and capability development with South Korea’s military, the Republic of Korea Armed Forces, USFK provides the United States with a rapid-response contingency against North Korea, as the peninsula remains the primary area of operations for the subordinate unified command.
However, amid heightened tensions in the Indo-Pacific, USFK may assume broader regional responsibilities. Nikkei Asia reported that USFK commander General Xavier Brunson said on December 29, 2025, that the subordinate unified command would not only respond to threats on the Korean Peninsula, signaling a potentially expanded mission. Brunson also suggested the need for greater USFK “strategic flexibility.”
A primary driver of expanded USFK responsibilities is preparation for a potential Taiwan contingency, as China continues to develop military capabilities that challenge the Taiwan Strait’s strategic status quo.
As Taiwan and Japan expand defense spending and military capabilities, USFK may also be expected to play a critical role in deterring China’s ambition of “reunifying” Taiwan with the mainland.
New mission
Discussion of South Korea’s potential role in a Taiwan emergency was hinted at by former Defense Secretary Mark Esper. IF Seoul provided such support, USFK would likely assume an even more significant role.
The United States’ 2026 National Security Strategy places greater emphasis on homeland defense than the Indo-Pacific region. As a result, subordinate unified commands such as USFK may be expected to shoulder increased deterrence responsibilities and contingency planning.
Geographically, South Korea occupies a strategically important position in a potential conflict with China. Its access to the Yellow Sea and East China Sea enables support for US Forces Japan, which would likely play a more direct role in a Taiwan emergency than USFK.
USFK could also help deter North Korean provocations should Pyongyang attempt to overstretch US forces during a Taiwan crisis. Through early-warning data sharing with Tokyo, Seoul can also help monitor China’s growing ballistic missile capabilities that could approach Korean airspace.
Japan, which has ended its strategic ambiguity on Taiwan under Prime Minister Sanae Takaichi, could play a major role in evacuating essential personnel, including American and Taiwanese officials. USFK could assist evacuation efforts and use South Korea as a processing hub for key personnel.
Japan’s potential direct intervention in a Taiwan emergency, along with US Forces Japan engaging the Chinese military, would make Japan a target for Beijing’s ballistic missiles. South Korea, by contrast, may avoid direct combat, positioning it as a safer staging zone for evacuees.
South Korea is a major producer of artillery and missiles, and USFK could facilitate the movement of wartime supplies to key Indo-Pacific locations, including Japan and Guam. As Seoul assists Washington in revitalizing shipbuilding, USFK could also support maintenance and naval production during wartime.
USFK could also contribute to intelligence gathering on Chinese naval movements. South Korea’s National Intelligence Service, working with USFK, could track elements of China’s Northern Fleet and key PLA staging areas in a conflict scenario.
China’s potential reaction
Beijing is unlikely to remain passive in response to expanded USFK involvement or deployments and could seek to pressure Seoul through diplomatic coercion, military threats or hybrid warfare.
Chinese state media has characterized South Korea as the weakest link among US allies in East Asia when it comes to supporting Taiwan.
USFK could potentially use South Korea’s southern regions and islands to disrupt PLA reinforcements in a Taiwan contingency, including at locations such as Jeju. This possibility raises the risk that South Korea could become a Chinese target for retaliation.
Seoul has established a Jeju Naval Task Force command for the ROK Navy on the island. However, local opposition to an expanded US military presence remains strong due to historical grievances of a violent US-backed crackdown and fears of becoming a target of Chinese ballistic missiles.
Public opinion data suggests conditional support for involvement in a Taiwan contingency. While only about 20% of South Koreans support sending troops to Ukraine, a majority favors some form of support for Taiwan.
An August 2022 JoongAng Ilbo survey found that 42% support a limited logistical role and 22.5% support direct military operations alongside US forces, totaling 64.5% support for indirect or direct involvement.
To mitigate potential retaliation on the Peninsula, USFK should strengthen air and missile defenses, including THAAD deployments, in the event of a Taiwan contingency.
Enhanced logistical coordination, wartime production, humanitarian and operations and intelligence sharing should also be key priorities for USFK and South Korea as the potential for a Taiwan war rises.
Julian McBride is a defense analyst and contributing editor at 19FortyFive.
