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
In 1971 the U.S. authorized the ARVN to carry out an offensive operation aimed at cutting the Ho Chi Minh Trail in southeastern Laos. Besides attacking the PAVN logistical system (which would buy time for the U.S. withdrawal) the incursion would be a significant test of Vietnamization. Backed by U.S. air and artillery support (American troops were forbidden to enter Laos), the ARVN moved across the border along Route 9, utilizing the abandoned Marine outpost of Khe Sanh as a jumping-off point. At first, the incursion went well, but unlike the Cambodian operation of 1970, the PAVN decided to stand and fight, finally mustering around 60,000 men on the battlefield.