To secure that two-year interval – from the Paris peace accords of January 1973 to the fall of Saigon in April 1975 – Nixon and his national security adviser, Henry Kissinger, subjected the people of Vietnam to four years of bombardment, which they extended to neighboring Cambodia and Laos. More than 20,000 American soldiers died during that period. The Vietnamese, Cambodian, and Laotian death toll was many times higher.