The war was the central issue of the 1972 presidential election. Nixon's opponent, George McGovern, campaigned on a platform of withdrawal from Vietnam. Nixon's National Security Adviser, Henry Kissinger, continued secret negotiations with North Vietnam's Le Duc Tho. In October 1972, they reached an agreement. However, South Vietnamese President Thieu demanded massive changes to the peace accord. When North Vietnam went public with the agreement's details, the Nixon administration claimed that the North was attempting to embarrass the President. The negotiations became deadlocked. Hanoi demanded new changes. To show his support for South Vietnam and force Hanoi back to the negotiating table, Nixon ordered Operation Linebacker II, a massive bombing of Hanoi and Haiphong. The offensive destroyed much of the remaining economic and industrial capacity of North Vietnam. Simultaneously Nixon pressured Thieu to accept the terms of the agreement, threatening to conclude a bilateral peace deal and cut off American aid.
On 15 January 1973, Nixon announced the suspension of offensive action against North Vietnam. The Paris Peace Accords on "Ending the War and Restoring Peace in Vietnam" were signed on 27 January 1973, officially ending direct U.S. involvement in the Vietnam War. A cease-fire was declared across North and South Vietnam. U.S. POWs were released. The agreement guaranteed the territorial integrity of Vietnam and, like the Geneva Conference of 1954, called for national elections in the North and South. The Paris Peace Accords stipulated a sixty-day period for the total withdrawal of U.S. forces. "This article," noted Peter Church, "proved... to be the only one of the Paris Agreements which was fully carried out."