The Truman Doctrine, proposed by then-president Harry S. Truman in 1947, was successful. In general terms, the Doctrine turned the United States from a passive country in international conflicts to an active one, sending military aid or money to help countries stave off Communism.
The Truman Doctrine was a specific measure to help the Greece fight off the rising threat of the Soviet-backed Greek Communist Party. Prior to U.S. involvement, the English had backed the Greeks against the Soviet threat, but they withdrew support. The overwhelming goal of the Truman Doctrine was to help free people fight the threat of totalitarian regimes. The Greeks joined the North Atlantic Treaty Organization shortly after driving off the Greek Communist Party with U.S. aid.