In the late 1980s, Vietnamese units stationed in Cambodia represented a military force that had broken away from its revolutionary tradition and had become an army of occupation, a dramatic role change in view of the fact that its most formidable adversaries, the Khmer Rouge, were fellow commÍÍÍÍunists and former allies. Consistently designated by Hanoi as "the Vietnamese volunteer army in Kampuchea," the Vietnamese force, comprising some ten to twelve divisions, was made up of conscripts who supported a "regime of military administration."

Military units totalling as many as 200,000 troops invaded Cambodia at the end of 1978 to eradicate the Khmer Rouge regime of Democratic Kampuchea and to install a more pliant government in Phnom Penh. After several years, Vietnam ostensibly began to decrease the size of its military contingent in Cambodia. The first recorded, but unannounced, withdrawal occurred in June 1981, when Vietnam's 137th Division returned home. In July 1982, Hanoi announced publicly that as an "act of goodwill" it would withdraw an unspecified number of troops from Cambodia. These withdrawals became annual occurrences. In 1986 Vietnamese sources announced a pullout of 12,000 troops. In November 1987, an additional 20,000 Vietnamese military personnel were withdrawn. These retrenchments were conducted with considerable publicity and fanfare, including departure ceremonies in Phnom Penh and featuring medals for commanders and citations for units. Skeptics, however, contended that these movements were merely troop rotations. A 1987 study conducted by Chulalongkorn University in Bangkok reached the same conclusion, after its researchers interviewed groups of Vietnamese defectors.

Hanoi publicly committed itself to withdraw its occupation forces by 1990. It first announced this decision following an August 1985 meeting of Vietnamese, Laotian, and Cambodian foreign ministers. The commitment to a pullout engendered continuing discussion, both by foreign observers and by Indochinese participants. What emerged was the clarifying qualification that a total Vietnamese military withdrawal was contingent upon the progress of pacification in Cambodia and upon the ability of the KPRAF to contain the insurgent threat without Vietnamese assistance. Prime Minister Hun Sen declared in a May 1987 interview that "if the situation evolves as is, we are hopeful that by 1990 all Vietnamese troops will be withdrawn ... [but] if the troop withdrawal will be taken advantage of, we will have to negotiate to take appropriate measures... ." Shortly thereafter, a KPRAF battalion commander told a Phnom Penh press conference that "Vietnamese forces could remain in Cambodia beyond 1990, if the Khmer Rouge resistance continues to pose a threat." In an interview with a Western correspondent, Vietnamese Foreign Minister Nguyen Co Thach repeated the 1990 withdrawal pledge, insisting that only foreign military intervention could convince Hanoi to change its plans. Some ASEAN and Western observers greeted declarations of a total pullout by 1990 with incredulity. Departing Vietnamese units rep 100ortedlydly left equipment behind in Cambodia, and it was suggested that they easily could return if it looked as though a province might be lost.

As Hanoi's military presence in Cambodia approached its ninth year, it appeared that the Vietnamese troops stationed there were not frontline veterans. Most of Vietnam's main force units and its best troops were deployed in the Red River Delta or on Vietnam's northern border to contain any armed threat from China. Units in Cambodia were composed of conscripts from the southern provinces of Vietnam, or, according to refugee accounts, of military misfits and "troublemakers." Some Vietnamese defectors in Thailand declared that they had volunteered for military service to get out of Vietnam and to have an opportunity for resettlement in third countries.

Vietnam's presence in Cambodia reportedly consumed 40 to 50 percent of Hanoi's military budget. Although substantial portions of the cost had been underwritten by Soviet grant aid, Vietnamese troops in Cambodia apparently were on short rations. Radio Hanoi reportedly commented on troops "dressed in rags, puritanically fed, and mostly disease ridden." The parlous state of Vietnamese forces in Cambodia also was the subject of a report by the director of an Hanoi military medical institute. According to media accounts, the report acknowledged that Vietnamese troops in the country suffered from widespread and serious malnutrition and that beriberi occurred in epidemic proportions.

The Vietnamese military headquarters in Cambodia was located at Chamka Morn in Phnom Penh. In the mid-1980s, it was responsible to the Vietnamese Fourth Corps commander, at that time General Le Duc Anh (subsequently promoted to minister of national defense). Vietnamese military authorities divided Cambodia into four military regions. These areas probably coincided with KPRAF regions. Each of these regions, in turn, corresponded to a Vietnamese military front that exercised tactical responsibility over it. The four Vietnamese military fronts were Front 479, headquartered at Barai Toek Thla Airport, Siemreab-Otdar Meanchey Province Front 579, at Stoeng Treng City, Stoeng Treng Province Front 779, at the Chhupp rubber plantation, Kampong Cham Province and Front 979, at Somrong Tong, Kampong Spoe Province. Front 479 was considered the most critical because of heavy insurgent activity in the area. A Special Military Administrative Zone was also created, comprising the vital heartland of the country around the Tonle Sap and the alluvial plain to the southeast. The relationship of the zone to the military regions and to the fronts was undetermined. Along the Cambodian coast, the Vietnamese established another type of military jurisdiction. Naval Zone Five comprised the shore lines of Kaoh Kong and Kampot provinces and their contiguous territorial waters. The headquarters of the naval zone was at Kampong Saom.

Vietnamese military advisers also were detached to serve with KPRAF main and provincial forces down to the battalion, and perhaps even the company, level. The functions and the chain of command of these advisers remained unknown, except that it could be assumed that they reported to the Vietnamese military region or front headquarters.

Data as of December 1987