Cambodian communist movement. Formed to resist the right-wing, US-backed regime of Lon Nol after the latter’s military coup in 1970, the Khmer Rouge, with Vietnamese assistance, first dominated the countryside and then captured the capital Phnom Penh (1975). Under Pol Pot it began a bloody purge, liquidating nearly the entire professional élite as well as most of the government officials and Buddhist monks. The majority of the urban population were relocated on worksites in the countryside where large numbers perished. The regime was responsible for an estimated 2 million deaths in Cambodia (Kampuchea), and for the dislocation of the country’s infrastructure. Frontier disputes with Vietnam provoked an invasion by the latter in 1978 which led to the overthrow of the Khmer Rouge regime, although its forces continued a guerrilla war against the Vietnamese-backed Heng Samrin regime from bases in Thailand. As the Party of Democratic Kampuchea, with its former leader Pol Pot still influential, it agreed to join the UN-backed Supreme National Council, following the peace agreement of October 1991. However, the Khmer Rouge refused to participate in multiparty elections in 1993 and continued to wage a guerrilla war against the elected government until 1998–99, when most of its members either joined or surrendered to the government forces.