In 1949, the prospect of further Communist expansion prompted the United States and 11 other Western nations to form the North Atlantic Treaty Organization (NATO). The Soviet Union and its affiliated Communist nations in Eastern Europe founded a rival alliance, the Warsaw Pact, in 1955.

In the immediate post-World War II period, Europe remained ravaged by war and thus susceptible to exploitation by an internal and external Communist threat. In a June 5, 1947, speech to the graduating class at Harvard University, Secretary of State George C. Marshall issued a call for a comprehensive program to rebuild Europe.

Cold War, the open yet restricted rivalry that developed after World War II between the United States and the Soviet Union and their respective allies.

As the world began recovering from World War II, the first General Assembly of the United Nations met in London in January 1946, and created the United Nations Atomic Energy Commission. Part of their charge was to eliminate all weapons of mass destruction, including the atomic bomb.

The United States emerged from World War II as one of the foremost economic, political, and military powers in the world. Wartime production pulled the economy out of depression and propelled it to great profits. In the interest of avoiding another global war, for the first time the United States began to use economic assistance as a strategic element of its foreign policy and offered significant assistance to countries in Europe and Asia struggling to rebuild their shattered economies.

Growing out of post-World War II tensions between the two nations, the Cold War rivalry between the United States and the Soviet Union that lasted for much of the second half of the 20th century resulted in mutual suspicions, heightened tensions and a series of international incidents that brought the world’s superpowers to the brink of disaster.

It is often said that the North Atlantic Treaty Organization was founded in response to the threat posed by the Soviet Union. This is only partially true. In fact, the Alliance’s creation was part of a broader effort to serve three purposes: deterring Soviet expansionism, forbidding the revival of nationalist militarism in Europe through a strong North American presence on the continent, and encouraging European political integration.

In May 1955, the “treaty of mutual friendship, co-operation and mutual assistance” was signed between the People’s Republic of Albania, the People’s Republic of Bulgaria, the Hungarian People’s Republic, the German Democratic Republic, the Polish People’s Republic, the Rumanian People’s Republic, the Union of Soviet Socialist Republics, and the Czechoslovak Republic. It was the Communist counteraction to NATO (North Atlantic Treaty Organization).

Treaty of Friendship, Cooperation and Mutual Assistance Between the People's Republic of Albania, the People's Republic of Bulgaria, the Hungarian People's Republic, the German Democratic Republic, the Polish People's Republic, the Rumanian People's Republic, the Union of Soviet Socialist Republics and the Czechoslovak Republic, May 14, 1955

Primary sources. This collection focuses on The Truman Doctrine. It includes 67 documents totaling 574 pages, a lesson plan, and links to oral histories.