b) Containing Communism

The main U.S. objective in the Korean War was containing Communism, a key element of the Truman Doctrine and the broader U.S. Cold War strategy. The war began when communist North Korea, supported by the Soviet Union and China, invaded South Korea. The U.S., leading a United Nations coalition, intervened to support South Korea, reflecting the policy of containment aimed at preventing the spread of communism beyond its existing borders.