In the 1960s, Cambodia became more and more involved into the Vietnam War; to avoid conflicts with the USA and with communist North Vietnam, Prince Sihanouk declared Cambodia a neutral state, but he allowed North Vietnam to transport military goods through Cambodian territory to supply the communist Vietcong guerilla in South Vietnam with weapons and equipment. On 18th March 1970, General Lon Nol lead a military coup against Sihanouk and formed a pro-American government, which gave the US Army permission to fight against the Vietnamese communists on Cambodian territory. General Lon Nol proclaimed Cambodia the “Khmer Republic” in October, and the country got a new flag and national anthem, which remained in use until the communist Khmer Rouge seized power in 1975.
Special thanks to: Erik Davis for the translation of the lyrics.