From the 1950s, Khmer Rouge was the name of a leftist-socialist organization in Cambodian politics. However in the 1970s the name came to be identified with the Communist Party of Kampuchea (CPK), known during the 1980s and 1990s as the "Party of Democratic Kampuchea." They became infamous for their role in the genocide of between 900,000 and 2 million Cambodians under the leadership of Pol Pot.
Until the mid-1990s the leadership of the CPK was largely unchanged since the 1960s. The Standing Committee of the Central Committee ("Party Center") comprised Pol Pot, Nuon Chea[?], Ta Mok, Khieu Samphan[?], Ke Pauk[?], Ieng Sary[?], Son Sen[?], Yun Yat[?], and Ieng Thirith[?]. The leadership of the Khmer Rouge had mostly studied advanced degrees in France.
The Khmer Rouge army (the National Army of Democratic Kampuchea), aided by North Vietnam and supported by Norodom Sihanouk, began a revolution in response in 1970, quickly gaining control over most of the country. In April 1975 they finally overthrew Lon Nol, to establish Democratic Kampuchea.
The factors which led to the Khmer Rouge victory remain extremely controversial especially in the United States where it is part of a broader controversy over United States involvement in southeast Asia. Some have argued that the rise of the Khmer Rouge was the result of the United States pullout from Vietnam and Congressional refusal to fund the Lon Nol government. In response, it has been counterargument that the Khmer Rouge would not have risen to power if the Nixon had not conducted bombing of Cambodia and supported Lon Nol's coup in 1970.
The ideology of the Khmer Rouge was a potent combination of Stalinism, Maoism, and French anticolonialism. From Stalinism, the Khmer Rouge derived the principle that opponents to the regime could not be reformed and must be killed. From Maoism, the regime derived the notion that the entire society must be restructured to create agricultural communes. From French anticolonialism, the Khmer Rouge adopted the principle that Cambodia must be isolated from the rest of the world.
In an effort to create a classless utopian society the new government carried out a radical program (Year Zero) of emptying the urban areas, closing schools and factories, abolishing banking and currency, outlawing all religions, ending all private propery, and herding the population into collective farms. Unlike other communist regimes, there was no cult of personality, and the leaders of the Khmer Rouge maintained a low, almost anonymous profile.
Large segments of the population including intellectuals, anyone connected with the previous regime, and anyone suspected of pro-Vietnamese sympathies were targeted for murder. Depending on the source a reported 15% to 40% of the population died between 1975 and 1979 (1 to 3 million people). These killings were taken within a climate of extreme paranoia in which the regime imagined elaborate conspracies involving the Americans, the Russians, and the Vietnamese.
The Khmer Rouges were also planning to regain land lost centuries ago to Vietnam. In 1978, after several years of border conflict, Vietnamese troops invaded in December, deposing the Khmer Rouge government within two weeks, by January 7, 1979. Ironically, the Vietnamese were helped by widespread defections of Khmer Rouge in eastern Cambodia who faced with the certainty of being executed on the imagined grounds of helping the Vietnamese should the regime remain, decided to help the Vietnamese overthrow the Khmer Rouge. The Khmer Rouge, however, continued to control an area near the Thai border. In 1985 Khieu Samphan[?] officially succeeded Pol Pot as head of the Khmer Rouge.
All Cambodian political factions signed a treaty in 1991 calling for elections and disarmament. But in 1992 the Khmer Rouge resumed fighting and the following year they rejected the results of the elections. There was a mass defection in 1996 when around half the remaining soldiers (about 4,000) left. Factional fighting in 1997 led to Pol Pot's trial and imprisonment by the Khmer Rouge. Pol Pot died in April 1998, and Khieu Samphan surrendered in December 1998. On December 29, 1998 the remaining leaders of the Khmer Rouge apologized for the genocide of over 1 million of their countrymen in the 1970s. By 1999 most members had surrendered, or been captured.
Although it is widely believed that the leaders of the Khmer Rouge were involved in crimes against humanity, trials of the leaders remain stalled and it is highly unlikely that any of them will be brought to justice. Many observers believe that the slow progress of Khmer Rouge trials is in large part due to the fact that many members of the current government were former officials of the Khmer Rouge and may be implicated in crimes.