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.
Role of the United States in the Vietnam War
By 1969 the policy of non-alignment and neutrality had worn thin for Prince Sihanouk, ruler of Cambodia. Pressures from the right in Cambodia caused the prince to begin a shift away from the pro-left position he had assumed in 1965–1966. He began to make overtures for normalized relations with the U.S. and created a Government of National Salvation with the assistance of the pro-American General Lon Nol. Seeing a shift in the prince's position, President Nixon ordered the launching of a top-secret bombing campaign, targeted at the PAVN/NLF Base Areas and sanctuaries along Cambodia's eastern border.
On March 18, 1970, Sihanouk, who was out of the country on a state visit, was deposed by a vote of the National Assembly and replaced by General Lon Nol. Cambodia's ports were immediately closed to North Vietnamese military supplies, and the government demanded that PAVN/NLF forces be removed from the border areas within 72 hours. On March 29, 1970, the Vietnamese had taken matters into their own hands and launched an offensive against the Cambodian army. A force of North Vietnamese quickly overran large parts of eastern Cambodia reaching to within of Phnom Penh allowing their allies, the Chinese-supported Khmer Rouge to extend their power. Nixon ordered a military incursion into Cambodia by U.S. and ARVN troops in order to both destroy PAVN/NLF sanctuaries bordering South Vietnam and to buy time for the U.S. withdrawal. During the Cambodian Campaign, U.S. and ARVN forces discovered and removed or destroyed a huge logistical and intelligence haul in Cambodia.