Claim: The United States fought in the Vietnam War to prevent the spread of communism.

Containment is a geopolitical strategy to stop the expansion of an enemy . It is best known as the Cold War policy of the United States and its allies to prevent the spread of communism . 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 .   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 , 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 .   Although the term `` containment '' was first used for the strategy in the 1940s , there were major historical precedents familiar to Americans and Europeans . In the 1850s anti-slavery forces in the United States developed a containment strategy -LRB- they did not use the word -RRB- for stopping the expansion of slavery and forcing its collapse . Historian James Oakes explains the strategy :  `` The federal government would surround the south with free states , free territories , and free waters , building what they called a ` cordon of freedom ' around slavery , hemming it in until the system 's own internal weaknesses forced the slave states one by one to abandon slavery . ''   Following the 1917 communist revolution in Russia , there were calls by Western leaders to isolate the Bolshevik government , which seemed intent on promoting worldwide revolution . In March 1919 , French Premier Georges Clemenceau called for a cordon sanitaire , or ring of non-communist states , to isolate the Soviet Union . Translating this phrase , U.S. President Woodrow Wilson called for a `` quarantine . '' Both phrases compare communism to a contagious disease . The U.S. initially refused to recognize the Soviet Union , but President Franklin D. Roosevelt reversed the policy in 1933 , hoping to expand American export markets . The Munich Agreement of 1938 was an attempt to contain Nazi expansion in Europe ; it failed . The U.S. tried to contain Japanese expansion in Asia in 1937-41 , and Japan reacted with its attack on Pearl Harbor .   After Germany invaded the USSR in 1941 during World War II , the U.S. and the Soviet Union found themselves allied in opposition to Germany . The policy was rollback , to defeat Germany , Italy , and Japan .