History of the United States (1964–1980)
The growing Watergate scandal was a major disaster for Nixon, eroding his political support in public opinion and in Washington. However he did manage to secure large-scale funding for South Vietnam, much of which was wasted. The United States withdrew its troops from Vietnam before the Paris Peace Accords in 1973. However, Watergate resulted in significant Democrat gains in the 1974 midterm elections and when the new 94th Congress convened the following January, it immediately voted to terminate all aid to South Vietnam in addition to passing a bill forbidding all further US military intervention in Southeast Asia. President Ford was against this, but as Congress had a veto-proof majority, he was forced to accept. South Vietnam rapidly collapsed as the North invaded it in force, and Saigon fell to the NVA on April 30, 1975. Later nearly one million Vietnamese managed to flee to the U.S. as refugees. The impact on the U.S. was muted, with few political recriminations, but it did leave a "Vietnam Syndrome" that cautioned against further military interventions anywhere else. Nixon (and his next two successors Ford and Carter) had dropped the containment policy and were not willing to intervene anywhere.
United States–Vietnam relations
In the United States, the issue of normalizing relations with Vietnam was complicated by Vietnam's invasion of Cambodia in December 1978, the continuing plight of Vietnamese refugees, and the unresolved MIA issue. In 1987, under President Ronald Reagan, the United States continued to enforce the trade embargo imposed on Hanoi in 1975 and barred normal ties as long as Vietnamese troops occupied Cambodia. Any efforts to improve relations remained closely tied to United States willingness to honor its 1973 aid commitment to Vietnam and to Hanoi's failure to account for the whereabouts of more than 2,400 MIAs in Indochina. From the signing of the Paris agreements in 1973 until mid-1978, the Vietnamese had routinely stressed the linkage between the aid and MIA issues. Beginning in mid-1978, however, Hanoi dropped its insistence that the MIA and aid questions be resolved as a precondition for normalization and stopped linking the MIA question to other unresolved matters between the two countries. Vietnamese leaders contrasted their restraint on the MIA issue with its alleged political exploitation by the United States as a condition for normal relations. As additional signs of goodwill, Hanoi permitted the joint United States-Vietnamese excavation of a B-52 crash site in 1985 and returned the remains of a number of United States servicemen between 1985 and 1987. Vietnamese spokesmen also claimed during this period to have a two-year plan to resolve the MIA question but failed to reveal details.