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 The U.S. 101st Airborne Division left South Vietnam, the last U.S. ground combat division to be withdrawn from South Vietnam.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
Australian–Thai Peace Treaty end its state of war with Britain and accept Britain's peace terms. It insisted on the trial of collaborators with the Japanese—which the Thais resented—and on reparations in relation to the tin mines. The Thais did try and imprison former Prime Minister Plaek Phibunsongkhram in order to forestall any Allied tribunal before signing the Anglo-Thai Peace Treaty on 1 January 1946. After the British peace treaty, Eastman exchanged notes with the Thai negotiator, Prince Vivadhanajaya Jayanta, confirming that a separate treaty with Australia would be signed no later than 3 April. The government in Canberra considered withdrawing him from Bangkok