Containment refers to the foreign policy strategy of the United States in the early years of the Cold War. The term was first used by George F. Kennan in 1947 in his Foreign Affairs article "The Sources of Soviet Conduct," better known as the X Article.

Kennan argued that the primary goal of the United States should be to prevent the spread of Communism to non-Communist nations, that is, to "contain" Communism within its borders. The Truman Doctrine aimed at this goal, and containment was one of its key principles.