Definition: United States policy to "support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures." The doctrine was announced on March 12th 1947 by US President Harry Truman in response to crises within Greece and Turkey, nations which American believed were in danger of falling into the Soviet sphere of influence. The speech promised monetary aid and military advisors to Greece and Turkey, but the doctrine was expanded worldwide as part of the Cold War to cover assistance to all nations threatened by communism and the Soviet Union, involving the US with western Europe, Korea and Vietnam among others.
A major part of the doctrine was the policy of containment. The Truman Doctrine was developed in 1950 by NSC-68 (National Security Council Report 68) which assumed the Soviet Union was trying to spread its power across the whole world, decided that the US should stop this and advocated a more active, military, policy of containment, fully abandoning previous US doctrines like Isolationism. The resulting military budget rose from $13 billion in 1950 to $60 billion in 1951 as the US prepared for the struggle.
Examples: The West feared a communist invasion, both physical and ideological. The US countered with the Truman Doctrine with its policy of containment to stop communism spreading...
