The Cold War consisted of containing the communist countries where they already were. No further expansion. The Communists tried expanding south of Korea's 38th Parallel in 1950-1953 (Korean War); they failed. The Communists tried expanding into Central America & South America (Che Guevara, one of Castro's Lieutenants), they failed (US Special Forces-Green Berets). The Communists tried expanding south of Vietnam's 17th Parallel from 1955 through 1975 (Vietnam War); they succeeded. During the Vietnam War, there was a second meaning to the word "containment." That was keeping the Vietnam War in Vietnam. Not allowing the war to spread to other countries, and NOT involving the Communist Superpowers (Soviet Union/Red China). Thus, the Vietnam War was fought as a "Limited War"; Limited in the area in which the fighting was to occur AND limited to the use of conventional weapons (NO ATOMIC WEAPONS WOULD BE USED). The US did have a contingency plan to use NUCLEAR WEAPONS FOR BOTH THE KOREAN WAR & VIETNAM WAR.
To contain communism. The Korean & Vietnam Wars were part of that containment policy.
Containment
President Harry Truman isssued the policy of containment
containment-
Answer this question… By refusing to back down to Soviet aggression