The United States wanted to support South Korea primarily to contain communism, prevent the spread of Soviet and Chinese influence, and maintain regional stability during the Cold War. When North Korea invaded South Korea in 1950, the US viewed it as part of a larger communist expansion led by the Soviet Union and China and aimed to keep South Korea free from communist control to prevent a "domino effect" in the region. This intervention aligned with US policy to resist communism globally, fulfill commitments under international alliances, and protect strategic interests in Asia. Stationing US forces in South Korea also provided the United States with strategic military benefits, serving as a deterrent against North Korean aggression and helping to maintain peace in a critical region. The alliance has continued to serve broader US goals in the Indo-Pacific, including regional security and stability amid tensions involving China and North Korea. In summary, the US supported South Korea to stop communist expansion, protect its geopolitical interests, uphold alliances, and maintain regional peace and stability.