<P> Containment is a geopolitical strategy to stop the expansion of an enemy . It is best known as a Cold War foreign policy of the United States and its allies to prevent the spread of communism . As a component of the Cold War, this policy was a response to a series of moves by the Soviet Union to increase communist influence in Eastern Europe, China, Korea, Africa, and Vietnam . Containment represented a middle - ground position between detente and rollback . </P> <P> The basis of the doctrine was articulated in a 1946 cable by U.S. diplomat George F. Kennan during the post-World War II administration of U.S. President Harry S. Truman . As a description of U.S. foreign policy, the word originated in a report Kennan submitted to U.S. Defense Secretary James Forrestal in 1947 . It was a report that was later used in a magazine article . It is a translation of the French cordon sanitaire, used to describe Western policy toward the Soviet Union in the 1920s . </P>

Why did the united states pursue a policy of containment