1978-1991 - Cambodian Civil War

On January 10, 1979, the Vietnamese installed Heng Samrin as head of state in the new People's Republic of Kampuchea (PRK). The Vietnamese army continued its pursuit of Pol Pot's Khmer Rouge forces. At least 600,000 Cambodians displaced during the Pol Pot era and the Vietnamese invasion began streaming to the Thai border in search of refuge. The international community responded with a massive relief effort coordinated by the United States through UNICEF and the World Food Program. More than $400 million was provided between 1979 and 1982, of which the United States contributed nearly $100 million. At one point, more than 500,000 Cambodians were living along the Thai-Cambodian border and more than 100,000 in holding centers inside Thailand.

Cambodia was in the midst of a bloody civil war between the People’s Republic of Kampuchea, the Russian-backed Vietnamese occupiers under their leader, Comrade Heng Samrin, a former Pol Pot general, and the coalition government of Democratic Kampuchea, a three-part resistance movement of communists and noncommunists, led by Pol Pot’s Khmer Rouge and supported by the Chinese. The latter group holds Cambodia’s seat in the United Nations. Guns were everywhere, handled as casually as shoes. It was a situation in which the Vietnamese troops ruled by day and Khmer Rouge roamed by night and the villagers faced the dilemma of living between implacable enemies, while they’re planting rice in the fields, the war comes to them.

Vietnam's occupation army of as many as 200,000 troops controlled the major population centers and most of the countryside from 1979 to September 1989. The Heng Samrin regime's 30,000 troops were plagued by poor morale and widespread desertion. Resistance to Vietnam's occupation continued, and there was some evidence that Heng Samrin's PRK forces provided logistic and moral support to the guerrillas.

A large portion of the Khmer Rouge's military forces eluded Vietnamese troops and established themselves in remote regions. The non-communist resistance, consisting of a number of groups which had been fighting the Khmer Rouge after 1975--including Lon Nol-era soldiers--coalesced in 1979-80 to form the Khmer People's National Liberation Armed Forces (KPNLAF), which pledged loyalty to former Prime Minister Son Sann, and Moulinaka (Movement pour la Liberation Nationale de Kampuchea), loyal to Prince Sihanouk. In 1979, Son Sann formed the Khmer People's National Liberation Front (KPNLF) to lead the political struggle for Cambodia's independence. Prince Sihanouk formed his own organization, FUNCINPEC, and its military arm, the Armee Nationale Sihanoukienne (ANS) in 1981.

Warfare followed a wet season/dry season rhythm after 1980. The heavily-armed Vietnamese forces conducted offensive operations during the dry seasons, and the resistance forces held the initiative during the rainy seasons. In 1982, Vietnam launched a major offensive against the main Khmer Rouge base at Phnom Melai in the Cardamom Mountains. Vietnam switched its target to civilian camps near the Thai border in 1983, launching a series of massive assaults, backed by armor and heavy artillery, against camps belonging to all three resistance groups. Hundreds of civilians were injured in these attacks, and more than 80,000 were forced to flee to Thailand. Resistance military forces, however, were largely undamaged.

In the 1984-85 dry season offensive, the Vietnamese again attacked base camps of all three resistance groups. Despite stiff resistance from the guerrillas, the Vietnamese succeeded in eliminating the camps in Cambodia and drove both the guerrillas and civilian refugees into neighboring Thailand. The Vietnamese concentrated on consolidating their gains during the 1985-86 dry season, including an attempt to seal guerrilla infiltration routes into the country by forcing Cambodian laborers to construct trench and wire fence obstacles and minefields along virtually the entire Thai-Cambodian border.

Within Cambodia, Vietnam had only limited success in establishing its client Heng Samrin regime, which was dependent on Vietnamese advisors at all levels. Security in some rural areas was tenuous, and major transportation routes were subject to interdiction by resistance forces. The presence of Vietnamese throughout the country and their intrusion into nearly all aspects of Cambodian life alienated much of the populace. The settlement of Vietnamese nationals, both former residents and new immigrants, further exacerbated anti-Vietnamese sentiment. Reports of the numbers involved vary widely with some estimates as high as 1 million. By the end of this decade, Khmer nationalism began to reassert itself against the traditional Vietnamese enemy.

By 1987, a Vietnamese military contingent of 140,000 troops, and a Khmer force -- a surrogate for the Vietnamese -- of 30,000 to 35,000 troops, which comprised the KPRAF of the new government in Phnom Penh, maintained tenuous control over the heartland of Cambodia. This territory included the population centers, the fertile rice-growing area around the Tonle Sap, and the main arteries of communication.

The combined Vietnamese-KPRAF military effort was opposed by disunited and factious but persistent insurgent forces belonging to each of the three components of the tripartite Coalition Government of Democratic Kampuchea (CGDK--see Coalition Government of Democratic. The insurgents had the capability to conduct long-range combat or reconnaissance patrols with as many as 100 troops. They could engage in small-scale propaganda missions, raids, and ambushes against poorly armed targets, such as militia outposts, and in sabotage against stationary, infrastructural objectives, such as bridges and railroad tracks. They lacked sufficient troop strength, heavy weapons, trained leadership, and dependable logistical support, however, for sustained combat operations. From their jungle havens deep within the country and from their bases near the Thai border, the insurgents were reputed to range widely throughout Cambodia.

Verifiable guerrilla actions, however, were confined to the northwestern provinces of Batdambang and Siemreab-Otdar Meanchey (the two provinces were combined into one by the government of the People's Republic of Kampuchea prior to 1980), which continued to be the centers of insurgent activity. Most foreign observers in the late 1980s assessed the military situation as being at a stalemate. The rebels lacked the capability, actual or potential, to drive out the Vietnamese occupation force, while the combined Vietnamese-KPRAF armies, at foreseeable force and equipment levels, were incapable of destroying the CGDK guerrilla units.

The tripartite CGDK opposed both the Vietnamese military presence in Cambodia and the government of the People's Republic of Kampuchea that had been installed in Phnom Penh by Hanoi. Each component of the coalition maintained its own force of armed combatants. Divided by deep-seated animosities among their leaders, these three distinctive and autonomous military forces were brought into a reluctant and uneasy coalition as a result of diplomatic activity by the Association of Southeast Asian Nations (ASEAN). The common goal of contesting the Vietnamese occupation, however, could not bridge the noncommunist coalition partners' deep suspicion toward the renascent Khmer Rouge. Throughout the 1980s, the three combatant forces remained unintegrated, and each maintained separate bases, command structures, and operational planning. An effort by ASEAN to unite the three resistance forces on the Thai border resulted, in May 1984, in the creation on paper of the Permanent Military Coordinating Committee, which apparently never functioned.

Limited tactical cooperation, however, occasionally was reported among the various coalition partners. In one rare example, the three forces participated jointly in a major operation in Batdambang Province in early 1986. Usually, Khmer Rouge units, under their shadowy zonal commanders, remained aloof from their coalition partners and, on occasion, even attacked their military forces and inflicted casualties. Such interfactional clashes were the subject of several complaints by Sihanouk, who charged over the years that Khmer Rouge guerrillas had "repeatedly ambushed and killed [his] troops." These allegations were the principal reason why he chose to step down from the presidency of the CGDK on a leave of absence in May 1987.

In 1986, Hanoi claimed to have begun withdrawing part of its occupation forces. At the same time, Vietnam continued efforts to strengthen its client regime, the PRK, and its military arm, the Kampuchean People's Revolutionary Armed Forces (KPRAF). These withdrawals continued over the next 2 years, although actual numbers were difficult to verify. Vietnam's proposal to withdraw its remaining occupation forces in 1989-90--the result of ongoing international pressure--forced the PRK to begin economic and constitutional reforms in an attempt to ensure future political dominance. In April 1989, Hanoi and Phnom Penh announced that final withdrawal would take place by the end of September 1989.

The military organizations of Prince Sihanouk (ANS) and of former Prime Minister Son Sann (KPNLAF) underwent significant military improvement during the 1988-89 period and both expanded their presence in Cambodia's interior. These organizations provide a political alternative to the Vietnamese-supported People's Republic of Kampuchea [PRK] and the murderous Khmer Rouge. In 1989, as the Cold War came to a close, Soviet aid to Vietnam and Cambodia disappeared and Vietnamese forces left Cambodia. The last Vietnamese troops left Cambodia in September of 1989.