During the Cold War, the United States played a pivotal role as both a superpower and a key player in the ideological struggle against communism, chiefly represented by the Soviet Union. The U.S. adopted a policy of containment aimed at preventing the spread of communism globally, which led to military involvements, such as in Korea and Vietnam, and an extensive arms race. Additionally, the U.S. engaged in diplomatic efforts through alliances like NATO and initiatives like the Marshall Plan to support economic recovery in Western Europe. The U.S.'s actions shaped international relations and ideologies during this period, ultimately contributing to the Cold War's conclusion.