Containment is a geopolitical strategic foreign policy pursued by the United States. It is loosely related to the term cordon sanitaire which was later used to describe the geopolitical containment of the Soviet Union in the 1940s. The strategy of "containment" is best known as a Cold War foreign policy of the United States and its allies to prevent the spread of communism after the end of World War II.
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, while also being regarded as the beginning of the cold war. Containment represented a middle-ground position between detente (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-WWII 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 U.S. Defense Secretary James Forrestal in 1947, which was later used in a magazine article.