Containment was a geopolitical strategic foreign policy pursued by the United States during the Cold War to prevent the spread of communism after the end of World War II. The name was loosely related to the term cordon sanitaire, which was containment of the Soviet Union in the interwar period.

As a component of the Cold War, this policy caused a response from the Soviet Union to increase communist influence in Eastern Europe, Asia, Africa, and Latin America. Containment represented a middle-ground position between détente (relaxation of relations) and rollback (actively replacing a regime). The basis of the doctrine was articulated in a 1946 cable by U.S. diplomat George F. Kennan during the post-World War II term of U.S. President Harry S. Truman. As a description of U.S. foreign policy, the word originated in a report Kennan submitted to US Defense Secretary James Forrestal in 1947, which was later used in a magazine article.