In 1947, President Harry S. Truman pledged that the United States would help any nation resist communism in order to prevent its spread. His policy of containment is known as the Truman Doctrine. The Truman Doctrine demonstrated that the United States would not return to isolationism after World War II, but rather take an active role in world affairs. To help rebuild after the war, the United States pledged $13 billion of aid to Europe in the Marshall Plan.
The United Stated had to contain communism from spreading through out Berlin, Korea, and Cuba.
