1972 in the Vietnam War the number of air raids against North Vietnam during all of 1971. Prime Minister Lon Nol declared President of Cambodia. Unlike the former Cambodian leader, Norodom Sihanouk, Lon Nol was a U.S. ally. The U.S. 101st Airborne Division left South Vietnam, the last U.S. ground combat division to be withdrawn from South Vietnam. The Khmer Rouge bombarded with artillery Phnom Penh, the capital city of Cambodia, killing more than 100 civilians. This was the heaviest attack on Phnom Penh since the Cambodian Civil War began in 1970. The United States boycotted peace negotiations in Paris with the North Vietnamese, citing
1954 in the Vietnam War government if he continued to implement democratic reforms. This letter was later cited by U.S. President Lyndon Johnson as the first step in the U.S. commitment to support South Vietnam. 8 September In Manila, the U.S., Australia, France, New Zealand, Pakistan, Philippines, Thailand, and the United Kingdom signed the treaty creating the Southeast Asia Treaty Organization (SEATO), a collective defense agreement that had among its objectives protecting Laos, Cambodia, and South Vietnam from communist aggression. 15 September Prime Minister Diệm faced the first crisis of his new government. He dismissed the Army chief of staff General Nguyễn Văn Hinh and