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 The U.S. 101st Airborne Division left South Vietnam, the last U.S. ground combat division to be withdrawn from South Vietnam.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
Peace treaty peace treaties known as the Peace of Westphalia. It initiated modern diplomacy, involving the modern system of nation-states. Subsequent wars were no longer over religion, but rather revolved around issues of state. This allowed Catholic and Protestant powers to ally, leading to a number of major realignments. The Korean War is an example of a conflict that was ended by an armistice rather than a peace treaty with the 1953 . The Korean War has never technically ended because a final peace treaty or settlement has not been achieved. A more recent example of a peace treaty is the 1973