The Truman Doctrine was established in 1947 to prevent the spread of communism following World War II. Named after President Harry S. Truman, the doctrine aimed to counter Soviet geopolitical expansion during the Cold War by providing political, military, and economic assistance to countries resisting communism. Initially directed towards Greece and Turkey, it signaled a shift in U.S. foreign policy, from isolationism to a more interventionist approach in global affairs. The Truman Doctrine laid the groundwork for American involvement in various conflicts and shaped the ideological framework of the Cold War era.