The Truman Doctrine was vital legislation aimed at limiting the spread of communism in post-World War II Europe. Announced in 1947 by President Harry Truman, it articulated the U.S. commitment to support nations resisting communist oppression. The doctrine initially focused on aiding Greece and Turkey, establishing a precedent for American intervention during the Cold War. Through military and economic assistance, the U.S. sought to contain communism, marking a shift in foreign policy towards a more active role in global affairs. The Truman Doctrine laid the groundwork for subsequent policies, including the Marshall Plan and involvement in conflicts around the world.