The U.S. military presence in South Korea comprises approximately 28,500 troops as part of the United States Forces Korea (USFK). These forces are deployed under the U.S.-South Korea Mutual Defense Treaty, established after the Korean War. Key components include: 1. Eighth Army: A field army with combat and support units. 2. Seventh Air Force: Operating out of Osan Air Base, it maintains air defence and combat capabilities. 3.