It officially started in 1947 with the Truman doctrine theorizing the " containment " policy , the Cold War had important consequences in Latin America . Latin America was considered by the United States to be a full part of the Western Bloc , called " free world " , in contrast with the Eastern Bloc , a division born with the end of World War II and the Yalta Conference held in February 1945 . It " must be the policy of the United States " , Truman declared , " to support free peoples who are resisting attempted subjugation by armed minorities or outside pressures . " Truman rallied to spend $ 400 million to intervene in the Greek civil war , while the CIA ( created by the National Security Act of 1947 ) intervention in Greece was its first act in its infancy . By aiding Greece , Truman set a precedent for U.S. aid to regimes , no matter how repressive and corrupt , that requested help to fight communists . Washington began to sign a series of defense treaties with countries all over the world , including the North Atlantic Treaty of 1949 , which created NATO , and the ANZUS in 1951 with Australia and New Zealand . Moscow responded to NATO and to the Marshall Plan in Europe with a plan which included the creation of the COMECON economic treaty and the Warsaw Pact defense alliance , as well as gathering Eastern Europe countries which had fallen under its sphere of influence . After the Berlin Blockade by the Soviet Union , the Korean War ( 1950 – 53 ) was one of the first conflicts of the Cold War , while the US succeeded France in the counter-revolutionary war against Viet-minh in Indochina
Yalta Conference
Yalta Conference
Latin America–United States relations