Containment
In 1949, the communists reached the border of Vietnam in the north. The result was that the Viet Minh were able to receive almost unlimited amounts of conventional weapons. The war in Vietnam transformed itself from an insurgency to a full war between armies in the remote areas of Vietnam. The international situation had also changed dramatically. The Soviet Union had put in place in Eastern Europe authoritarian regimes under its control. China had fallen to communist armies and war had broken out in Korea. The war in Korea helped build a U.S. perception of a general communist threat in Asia. Given China's involvement in Korea and its supply of weapons to the Viet Minh in Indochina, U.S. policymakers began giving support to the French administration.
After taking power in 1953, the administration of President Dwight D. Eisenhower accepted the Indochina policy established by the Truman Administration and its foreign policy corps essentially without modification. Support for the French colonial regime was continued, on the pretense that the French were fighting towards the ultimate independence of Vietnam, as well as the defeat of the communists. With the end of the Korean War, the U.S. became less interested in sustaining the French presence in Vietnam.
Read more about this topic: Background To The Vietnam War