During his first months in office, Nixon ordered the U.S. military to increase its pressure on the battlefield, while ordering the secret bombing of the B-52 on North Vietnamese base camps in Cambodia, the „small-scale bombings“ – as a signal of his willingness to intensify the war. He expected to supplement this military pressure with conciliatory negotiating conditions in the negotiations that began and diplomatic pressure on the Soviet Union, in the hope that the Soviet Union would encourage its North Vietnamese allies to negotiate seriously. But these forms of pressure did not make it closer to the end of the war. To buy time with the American people, Nixon began withdrawing troops from Vietnam and met on June 8 with South Vietnamese President Nguyen Van Thieu on Midway Island to announce the first increase in redeployment. From that moment on, the withdrawal of American troops never ceased. As the strength and capabilities of U.S. troops diminished, as the United States worked to build South Vietnam`s military capability through a program known as „Vietnamization.“ It would remain a constant question in the remaining years of the government as to whether the South Vietnamese could put in place combat capability, logistical and planning capabilities, and leadership at the national and military levels to stand alone against the North Vietnamese. In March 1970, the fall of Prince Norodom Sihanouk in Cambodia destroyed the fragile neutrality of that state when his successor Lon Nol asked the North Vietnamese to withdraw from their base camps along the South Vietnamese border. The North Vietnams responded by extending their presence to the west.
Nixon responded by ordering an April 30 „invasion“ of Cambodia by the United States and southern Vietnam. The action, limited by Nixon to a 30-kilometre stretch along the border and limited until the end of June, sparked violent protests on campuses in the United States. They culminated in the deaths of four students at Kent State University on May 4. The invasion of the North Vietnamese Army (NVA) base camps brought a large quantity of rice, weapons and ammunition and disrupted North Vietnamese command and logistics structures for months by buying time for Vietnamization and other withdrawals of U.S. troops. The basic elements of the agreement signed on January 27, 1973 at the Paris International Conference Centre for the end of the war and the restoration of peace in Vietnam presented the end of the fighting and the withdrawal of American forces. The United States has committed to halt all air and sea measures against North Vietnam and to dismantle or disable all mines in North Vietnam waters. Within two months of the signing of the agreement, all U.S.
armed forces and U.S. allies would depart for Vietnam. The United States was denied new war materials or deliveries to southern Vietnam and had to dismantle all military bases. GVN and NLF forces were allowed to stay where they were, but the ceasefire prevented the arrival of new troops, military advisers, military personnel – including technical personnel – of weapons, ammunition and war equipment from northern Vietnam or elsewhere. The disposition of the Vietnamese armed forces in southern Vietnam would be determined by both South Vietnamese parties in a spirit of „national reconciliation and concord“. In addition, the agreement required the return of all foreign military and civilians captured during the same two-month period. The two South Vietnamese sides would support the return of Vietnamese civilians. The United States and North Vietnam have promised to respect the principles of self-determination of the South Vietnamese people, which include free and democratic elections under international control.