The event that marked the beginning of the Cold War in 1947 is often attributed to the Truman Doctrine and the ensuing U.S. policy to contain communism. Faced with the spread of Soviet influence and the threat posed by communist movements in Europe and beyond, President Harry S. Truman announced the doctrine in March 1947, pledging support to countries resisting communism. This policy was a clear indicator of the ideological struggle between the United States and the Soviet Union, leading to an extended period of geopolitical tensions, military confrontations, and proxy wars that defined the Cold War era.