Formation The name "Revolutionary Army of Kampuchea" first emerged during the peasant uprising in
Samlout District,
Battambang province, in 1967. In practice, it was a general term for the independent armed groups of the Khmer Rouge, which were primarily divided into three factions: • The
Northeastern Group, led by
Pol Pot, was based in Cambodia's northeastern highlands among ethnic minorities. • The
Southwestern Group, led by
Hu Nim, operated in southern and southwestern Cambodia, in the
Cardamom and
Elephant Mountain ranges. • The
Eastern Group, led by
So Phim, was based in the densely populated eastern provinces between the
Mekong River and the Vietnamese border. In the years that followed, widespread dissatisfaction with the Sihanouk regime drove many Cambodians to flee government repression and join Khmer Rouge armed groups, leading to a rapid increase in the Revolutionary Army of Cambodia's ranks.
Alliance with Sihanouk The situation shifted in favour of the Khmer Rouge after the
March 18, 1970 coup, in which Prime Minister
Lon Nol, backed by the United States, ousted Head of State
Norodom Sihanouk while he was abroad. In response, Sihanouk announced the formation of the
National United Front of Kampuchea (FUNK) and the
Royal Government of National Union of Kampuchea (GRUNK), aligning himself with all forces opposed to Lon Nol, the strongest among them being the Khmer Rouge. As a result, the Revolutionary Army of Kampuchea was reorganized into the
Cambodian People's National Liberation Armed Forces (CPNLAF), absorbing armed groups loyal to Sihanouk. Sihanouk's influence in rural Cambodia allowed the Khmer Rouge to expand their power significantly. By 1973, they effectively controlled most of Cambodia's territory, though only a small portion of its population. Many Cambodians who supported the Khmer Rouge did so under the belief that they were fighting for Sihanouk's return. It was the CPNLAF that ultimately captured Phnom Penh and overthrew the
Khmer Republic in April 1975, establishing complete Khmer Rouge rule over Cambodia.
Purges and conflict with Vietnam Even before taking full power, the Khmer Rouge had begun purging the CPNLAF of Sihanouk's influence. From 1972 onward, after Richard Nixon's visit to China, Pol Pot's faction received increased backing from Beijing and gradually consolidated absolute control over the Communist Party of Kampuchea (CPK). Once they secured power, the Khmer Rouge immediately executed former officers of the Khmer National Armed Forces and their families, without trials or publicity, to eliminate potential enemies. Additionally, they conducted large-scale internal purges, not only removing remnants of Sihanouk's supporters but also eradicating any suspected dissent to centralise power further. The CPNLAF was restructured again into a formal national military force. Around 1976, it reverted to the name Revolutionary Army of Kampuchea, now as the unified national military of Democratic Kampuchea. Its air force was established in 1977. From as early as 1975, the Khmer Rouge launched cross-border attacks into Vietnam, burning villages, looting, and massacring civilians. Vietnam initially responded with restraint, limiting its actions to defensive counterattacks. However, as Pol Pot prepared for a full-scale war against Vietnam, he initiated another purge, executing numerous Khmer Rouge officials suspected of Vietnamese ties. Only a few, such as
Heng Samrin and
Hun Sen, managed to escape to Vietnam.
Swift war and defeat The war against Vietnam proved disastrous for the Khmer Rouge. Since the early 1970s, Vietnamese leaders had anticipated Khmer Rouge hostilities and took precautionary measures. From 1975 to 1978, Vietnam pursued a dual strategy: responding with restraint while simultaneously preparing for an
inevitable war in the southwest. By late 1978, Vietnam had established the
Kampuchean United Front for National Salvation (FUNSK), composed of former Khmer Rouge officials, soldiers, and Cambodian exiles. Under the banner of FUNSK, Vietnam formed a Volunteer Army to liberate Cambodia from the Khmer Rouge genocide. In just two weeks, Vietnamese forces obliterated the Khmer Rouge's main military divisions, captured Phnom Penh, and established the
People's Republic of Kampuchea.
U.S. and Chinese alliance Under the overwhelming assault of Vietnamese forces, the Khmer Rouge quickly disintegrated. Most of its remaining forces retreated to the Thai-Cambodian border, where they established long-term bases and maintained control over border areas for the next decade. Small remnants continued to engage in guerrilla warfare. By late 1979, the Khmer Rouge reorganized its armed groups into the National Army of Democratic Kampuchea, built from what remained of the Revolutionary Army of Kampuchea. Despite this, the weaknesses of the People's Republic of Kampuchea (PRK) led to its complete dependence on Vietnam—a country that had just emerged from two major wars, was now engaged in two border conflicts, and was struggling with a devastated economy. Vietnam's intervention to destroy the Khmer Rouge triggered strong reactions from its adversaries.
China, the
United States, and
ASEAN nations backed the formation of a Cambodian government-in-exile and the military alliance known as the
Coalition Government of Democratic Kampuchea (CGDK), which included the Khmer Rouge, the
Khmer People's National Liberation Front (KPNLF), and the royalist ANS (Armee Nationale Sihanoukiste). However, the Khmer Rouge remained the dominant military force within this three-party coalition, playing the leading role in prolonging the conflict against the Vietnam-backed Phnom Penh government for a decade. During this period, the Khmer Rouge continued to receive foreign support from China, the United States,
Thailand, and other countries hostile to Vietnam. However, this support was only enough to sustain its resistance—it was unable to regain its former strength. At its peak, the Khmer Rouge controlled around 20% of Cambodia's territory but only 5% of the population, compared to the Vietnam-backed Phnom Penh government.
Collapse With Vietnam's full support, the People's Republic of Kampuchea gradually consolidated its control over the country. It also actively pursued diplomatic measures to isolate the Khmer Rouge, including reconciliation with other Cambodian exile factions. In 1989, Vietnam withdrew its troops from Cambodia after securing the Phnom Penh government's stability and military strength. Peace negotiations led to the establishment of a coalition government for a constitutional monarchy with a multi-party system and democratic freedoms. As the Khmer Rouge refused to compromise, it became increasingly isolated. Although it continued military operations, boycotted elections, and rejected the results, it now faced opposition from Cambodia's new coalition government. This government included not only former Vietnamese-backed communists, led by Hun Sen, but also ex-Khmer Rouge allies, including non-communist and royalist factions such as Prince
Norodom Ranariddh's forces. Deprived of food supplies, trade goods, and international aid, the Khmer Rouge was forced into self-sufficiency. It had to abandon refugee camps, where international humanitarian aid had previously provided medicine and food. Public morale within Khmer Rouge-controlled areas collapsed. After Pol Pot's death in April 1998, the Khmer Rouge became a spent force, barely surviving. By late 1999, its last remaining commanders and soldiers surrendered to the Cambodian government, marking the final end of the Khmer Rouge. == Genocide ==