Truman Doctrine
This policy was set by President Harry Truman in a speech on March 12, 1947 stating that the U.S. would support Greece and Turkey with economic and military aid to prevent their falling into the Soviet Communism. Historians often consider it as the start of the Cold War, and the start of the containment policy to stop Soviet expansion.
The policy won the support of Republicans who controlled Congress and involved sending $400 million in American money, but no military forces, to the region. The effect was to end the Communist threat, and in 1952 both Greece and Turkey joined NATO.
President Harry Truman told Congress the Doctrine was "the policy of the United States to support free people who are resisting attempted subjugation by armed minorities or by outside pressures."