Let’s Learn about the Cold War: Part 5 - Containment Published Aug. 5, 2015 By Senior Airman Sean D. Smith Minot Air Force Base Public Affairs MINOT AIR FORCE BASE, N.D. -- After World War II, the Soviet Union was actively expanding into eastern Europe through both direct action and subversion, pushing communist influence onto countries like Poland, Iran and Turkey. President Truman made a pledge -- "It must be the policy of the United States to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures." This foreign policy is known as the Truman Doctrine, and it reflects the American diplomatic approach to holding back Soviet imperialism. In 1947, Truman asked congress to approve $400 million in aid for Greece and Turkey, to help them resist those efforts. That same year, Truman signed the National Security Act into law. The National Security Act reorganized the American armed forces and created the Central Intelligence Agency. Japan's surprise attack on Pearl Harbor sent a clear message to the American government about its need for greater intelligence gathering. To contain communism, information was needed, which led to heavy reliance on the CIA to get it throughout the Cold War -- but the Soviet Union was too large and too powerful to be held in check by any one nation. A pressing crisis at the time was the Berlin Blockade, with which the Soviet Union cut off access to certain parts of Berlin to deny supplies in an attempt to bring postwar Germany under communist control. The Western response to this action was the Berlin Airlift, an effort from numerous countries and their air forces, including the United States. The Berlin Airlift succeeded and direct conflict was avoided. It became clear that cooperation was key to holding back the USSR. While the Cold War is commonly seen as a conflict between the United States and the Soviet Union, but it was really the North Atlantic Treaty Organization, or NATO, and the Warsaw Pact, which included the Soviet Union and its allies. In 1949, the North Atlantic Treaty was signed in Washington D.C. Lord Hastings Ismay, the first Secretary General of NATO, stated that NATO's purpose was "...to keep the Russians out, the Americans in and the Germans down." Germany has since become an influential member of NATO. In 1949, NATO members agreed that attacks against any of them were attacks against all of them. Initially a political alliance of mutual aid and cooperation, NATO was forced into military action when war broke out between North and South Korea in 1950. Next Time: The Korean War