<P> The accords had been negotiated by United States National Security Advisor Kissinger and North Vietnamese politburo member Lê Đức Thọ . South Vietnamese President Nguyen Van Thieu was not involved in the final negotiations, and publicly criticized the proposed agreement . However, anti-war pressures within the United States forced Nixon and Kissinger to pressure Thieu to sign the agreement and enable the withdrawal of American forces . In multiple letters to the South Vietnamese president, Nixon had promised that the United States would defend Thieu's government, should the North Vietnamese violate the accords . </P> <P> In December 1974, months after Ford took office, North Vietnamese forces invaded the province of Phuoc Long . General Trần Văn Trà sought to gauge any South Vietnamese or American response to the invasion, as well as to solve logistical issues, before proceeding with the invasion . </P> <P> As North Vietnamese forces advanced, Ford requested Congress approve a $722 million aid package for South Vietnam, funds that had been promised by the Nixon administration . Congress voted against the proposal by a wide margin . Senator Jacob K. Javits offered "...large sums for evacuation, but not one nickel for military aid". President Thieu resigned on April 21, 1975, publicly blaming the lack of support from the United States for the fall of his country . Two days later, on April 23, Ford gave a speech at Tulane University . In that speech, he announced that the Vietnam War was over "...as far as America is concerned". The announcement was met with thunderous applause . </P> <P> 1,373 U.S. citizens and 5,595 Vietnamese and third country nationals were evacuated from the South Vietnamese capital of Saigon during Operation Frequent Wind . In that operation, military and Air America helicopters took evacuees to U.S. Navy ships off - shore during an approximately 24 - hour period on April 29 to 30, 1975, immediately preceding the fall of Saigon . During the operation, so many South Vietnamese helicopters landed on the vessels taking the evacuees that some were pushed overboard to make room for more people . Other helicopters, having nowhere to land, were deliberately crash landed into the sea after dropping off their passengers, close to the ships, their pilots bailing out at the last moment to be picked up by rescue boats . </P>

Who was president of united states in april 1975