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 The U.S. 101st Airborne Division left South Vietnam, the last U.S. ground combat division to be withdrawn from South Vietnam.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
Latvian–Soviet Peace Treaty Latvian–Soviet Peace Treaty The Latvian–Soviet Peace Treaty, also known as the Treaty of Riga, was signed on 11 August 1920 by representatives of the Republic of Latvia and Soviet Russia. It officially ended the Latvian War of Independence. In Article II of the treaty, Soviet Russia recognised the independence of Latvia as inviolable "for all future time". After World War I, Soviet Russia wanted to regain Latvia, since it had once been a part of the Russian Empire. The Red Army invaded Latvia in 1918 after the Latvian prime minister, Karlis Ulmanis, declared its independence. The Red Army was able