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 The U.S. 101st Airborne Division left South Vietnam, the last U.S. ground combat division to be withdrawn from South Vietnam.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
Treaty of San Francisco draws Japan into a military coalition directed against the Soviet Union; that the treaty was in effect a separate peace treaty; that the draft treaty violated the rights of China to Taiwan and several other islands; that the draft treaty, in violation of the Yalta agreement, did not recognize the Soviet Union's sovereignty over South Sakhalin and the Kuril Islands; and other objections. It was not until October 19, 1956, that Japan and the Soviet Union signed a Joint Declaration ending the war and reestablishing diplomatic relations. The ongoing Chinese Civil War and thus the question of which Chinese government