Richard Nixon was elected president in 1968 on a promise to end the Vietnam War. His policies of cutting the Ho Chi Minh supply trail through bombing campaigns destabilized Cambodia and Laos, while Vietnamization aimed to gradually withdraw U.S. troops by training South Vietnamese forces but ultimately failed as South Vietnam fell to North Vietnam in 1975. Nixon's presidency was cut short by the Watergate scandal after he was found to be involved in a cover up of White House-orchestrated burglaries at the Democratic National Committee headquarters. He resigned in 1974 to avoid impeachment.