Nixon was elected President and began his policy of slow disengagement from the war. The goal was to gradually
build up the South Vietnamese Army so that it could fight the war on its own. This policy became the cornerstone of the so-called
" Nixon Doctrine". As applied to Vietnam, the doctrine was called "Vietnamization". The stated goal of
Vietnamization was to enable the South Vietnamese army to increasingly hold its own against the NLF and the North Vietnamese
Army. The unstated goal of Vietnamization was that the primary burden of combat would be returned to ARVN troops and thereby
lessen domestic opposition to the war in the U.S.
During this period, the United States conducted a gradual troop withdrawal from Vietnam. Nixon continued to
use air power to bomb the enemy, at the expense of American troop incursions. Ultimately more bombs were dropped under the
Nixon Presidency than under Johnson's, while American troop deaths started to drop significantly. The Nixon administration
was determined to remove American troops from the theater while not destabilizing the defensive efforts of South Vietnam.
Many significant gains in the war were made under the Nixon administration, however. One particularly significant
achievement was the weakening of support that the North Vietnamese army received from the Soviet Union
and People's Republic of China. One of Nixon's main foreign policy goals had been the achievement of a
"breakthrough" in relations between the two nations, in terms of creating a new spirit of cooperation. To a large extent this
was achieved. China and the USSR had been the principal backers of the North Vietnamese army through large amounts of military
and financial support. The eagerness of both nations to improve their own US relations in the face of a widening breakdown
of the inter-Communist alliance led to the reduction of their aid to North Vietnam.
The morality of US conduct of the war continued to be an issue under the Nixon Presidency. Massacres were
only stopped after two American soldiers in a helicopter spotted the carnage and intervened to prevent their fellow Americans
from killing any more civilians.
In 1970, Nixon ordered a military incursion into Cambodia in order to destroy NLF sanctuaries bordering on
South Vietnam. This action prompted even more protests on American college campuses. Several students were shot and killed
by National Guard troops during demonstrations at Kent State.
One effect of the incursion was to push communist forces deeper into Cambodia, which destabilized the country
and in turn may have encouraged the rise of theKhmer Rouge, who seized power in 1975. The goal of the attacks,
however, was to bring the North Vietnamese negotiators back to the table with some flexibility in their demands that the South
Vietnamese government be overthrown as part of the agreement. It was also alleged that American and South Vietnamese casualty
rates were reduced by the destruction of military supplies the communists had been storing in Cambodia.
In an effort to help assuage growing discontent over the war, Nixon announced on October 12 1972 that the United States would withdraw 40,000 more troops before Christmas.
In the 1972 election, the war was once again a major issue in the United States. An antiwar candidate,
George McGovern, ran against President Nixon. Nixon's Secretary of State, Henry Kissinger, declared that "Peace is at
Hand" shortly before the voters went to the polls, dealing a death blow to McGovern's campaign, which had been facing an uphill
battle. However, the peace agreement was not signed until the next year, leading many to conclude that Kissinger's announcement
was just a political ploy. Kissinger's defenders assert that the North Vietnamese negotiators had made use of Kissinger's
pronouncement as an opportunity to embarrass the Nixon Administration to weaken it at the negotiation table. White House Press
Secretary Ron Ziegler on 30 November 1972 told the press that there would be no more public announcements concerning
American troop withdrawals from Vietnam due to the fact that troop levels were then down to 27,000. The US halted heavy bombing
of North Vietnam on December 30, 1972.
A campaign to bomb Vietnam's dikes and thus threaten the North Vietnamese food supply was employed to pressure
the North to concede, the details of which only began to surface much later.