Invasion and Liberation (1978-1979)
Border conflicts between the Khmer Rouge and Vietnam had escalated throughout 1977 and 1978. The Khmer Rouge regime, resentful of Vietnam's influence and convinced of Vietnamese territorial ambitions, launched raids across the border. These provocations gave Vietnam both justification and opportunity to act. On December 25, 1978, approximately 200,000 Vietnamese troops invaded Cambodia. Within two weeks, they had driven the Khmer Rouge from Phnom Penh and installed a new government.
On January 7-8, 1979, Vietnam established the People's Republic of Kampuchea (PRK) with Heng Samrin as president, Hun Sen as foreign minister, and Chea Sim as minister of interior. These leaders were Cambodian communists who had deserted the Khmer Rouge in 1977-78 and fled to Vietnam. For most Cambodians, the Vietnamese invasion brought profound relief. The genocide had ended. Families could reunite, speak freely, and practice Buddhism again. At the same time, Cambodia had traded one form of foreign control for another. The country that had liberated them was also Cambodia's traditional rival, and Vietnamese troops would remain for the next decade.
Famine and International Response (1979-1980)
The new government faced a country in ruins. Most civil servants, teachers, doctors, and skilled workers had been murdered or had fled abroad. Government offices sat empty. Hospitals lacked supplies, equipment, and trained personnel. The 1979 harvest had been disrupted by continued fighting, and severe famine threatened the population.
In June 1979, Jacques Beaumont and Francois Bugnion from the Red Cross and UNICEF became the first Western officials allowed to assess conditions in Cambodia. What they found shocked even these experienced humanitarian workers: a society, as one later described it, whose "very sinews had been ripped out." They watched children dying in hospitals for lack of basic care. Even government officials appeared hungry. The two men shared their own rations with interpreters.
When Beaumont and Bugnion returned and reported these conditions, their account triggered international alarm. However, bureaucratic complications and political disagreements delayed the relief effort. The PRK government, led by officials with little international experience and suspicious of Western organizations, hesitated to allow scores of foreign aid workers into the country. Red Cross and UNICEF wanted stringent monitoring of food distribution to ensure aid reached civilians rather than combatants. These negotiations consumed months.
Meanwhile, Oxfam took a different approach. In October 1979, Oxfam agreed to let PRK officials control distribution with only a small international team providing oversight, and pledged to give no aid to areas controlled by the Khmer Rouge. On October 13, the first Oxfam barge arrived at Cambodia's port. The same day, Red Cross and UNICEF began daily airlifts to Phnom Penh. Aid finally flowed four months after the initial assessment, a delay that humanitarian observers believed cost tens of thousands of lives.
Recovery Under Vietnamese Oversight (1980-1989)
Throughout the 1980s, Cambodia struggled back to its feet under Vietnamese supervision. The PRK government reversed many Khmer Rouge policies: it restored private property, reopened schools, reintroduced Buddhist practices, and allowed freedom of movement. Internal trade flourished as people could once again buy and sell goods in markets. Cities slowly repopulated as refugees returned from the countryside.
By 1989, Phnom Penh had grown to 800,000 residents. The city had markets, restaurants, cinemas, and shops. However, recovery remained incomplete and fragile. At night, even before the 10 p.m. curfew, Phnom Penh grew quiet "as a village," in the words of one long-term aid worker. Economic progress faced severe constraints from the international embargo. While Cambodia achieved bare self-sufficiency in food production, rice harvests throughout the 1980s never exceeded one million tons, and the population needed 900,000 to 1.5 million tons. Drought or floods could still trigger crisis. In 1988, Cambodia faced another near-famine requiring massive international assistance.
Industries, transportation networks, communication systems, and sanitation infrastructure saw minimal progress during the 1980s. Without international investment or trade relationships, the PRK government could do little beyond keeping basic services running. International donations of food and medicine often disappeared into what aid workers called the "black holes" of the Ministry of Commerce, becoming untraceable once turned over to Cambodian administrators.
The extent of Vietnamese control over the PRK remained a contentious issue. Vietnam maintained approximately 140,000 troops in Cambodia throughout the 1980s, funded by the Soviet Union. When Pen Sovann became prime minister in June 1981, he soon clashed with Le Duc Tho, Hanoi's chief advisor to the PRK. According to Pen Sovann's later account, Tho demanded 10,000 Vietnamese troops be stationed in each Cambodian province (over 200,000 total), that Cambodian families be relocated to pacify Khmer Rouge-infiltrated areas, and that Cambodian land be used for Vietnamese food production. Pen Sovann refused these demands. In December 1981, he was arrested and imprisoned in Hanoi for the next eleven years. Hun Sen became prime minister in January 1985, a position he held for 38 years. He still remains Cambodia's most powerful man.
After Vietnam withdrew its forces in 1989, the Phnom Penh government took initiatives that increased its popularity. It legalized property ownership, creating a real-estate boom in the capital. More significantly, it openly encouraged Buddhist practice, and hundreds of monasteries were restored, often funded by Cambodians living overseas.
The Refugee Crisis
At least 500,000 Cambodians fled to Thailand in the aftermath of the Khmer Rouge's fall, driven by fear, hardship, and the uncertainty of life under a Vietnamese-installed regime. Of these, approximately 200,000 people eventually resettled in other countries, particularly the United States, France, Australia, and Canada. The rest came under the control of three resistance groups camped along the Thai-Cambodian border.
The largest camp, Site 2, housed approximately 175,000 people by 1988. Nearly half were children under age nine, an entire generation growing up knowing only camp life. One resident, Chan Nak, had lost his leg to a landmine and had a daughter born in the camps who had never seen Cambodia. Camp life combined humanitarian assistance with harsh realities. The United Nations Border Relief Operation (UNBRO) provided 2,467 calories per day in food rations, medical care, and vocational training. Between 1982 and 1989, international donors spent $331 million on border relief, with the United States contributing $101 million and Japan $153 million.
However, the camps also experienced serious problems. Violence was endemic; Site 2 alone saw over 100 residents hospitalized monthly from assaults and attacks. Hand grenades sold for 80 cents. Water was scarce at just 18-20 liters per person per day. The camps served dual purposes: they were both refugee centers providing humanitarian services and military bases for resistance factions. This created accountability challenges, as international aid sometimes diverted to combatants rather than civilians once turned over to Cambodian camp administrators.
Despite these difficulties, cultural preservation efforts continued in the camps. Dance classes, art classes, and Bassak theater performances kept traditional arts alive. Many Cambodians spent years or even decades in these border camps before either returning home or resettling abroad, creating diaspora communities that remain active in Cambodian politics and cultural preservation today.
Cold War Diplomacy and Isolation
The PRK government received backing from Vietnam and the Soviet bloc, yet faced diplomatic isolation from the West. In a decision that would prove deeply controversial, the United Nations continued to recognize a coalition of ousted factions, including the exiled Khmer Rouge, as Cambodia's legitimate representative. In September 1980, U.S. Secretary of State Edmund Muskie announced that despite finding the Khmer Rouge's human rights record "abhorrent," the United States would support seating the regime at the UN to "prevent legitimization of a government installed by aggression and maintained by the presence of any invading army."
This position reflected Cold War priorities. China, the United States, and ASEAN countries opposed Vietnam's occupation and sought to impose political and economic costs until Vietnamese forces withdrew. Western countries, China, and ASEAN embargoed the PRK government, prolonging the guerrilla war throughout the 1980s. The Soviet Union bankrolled Vietnam's occupation, carrying the heavy financial burden of supporting Vietnamese forces in Cambodia.
Three resistance groups operated from Thai border camps: Prince Norodom Sihanouk's royalist forces, Son Sann's non-communist Khmer People's National Liberation Front (KPNLF), and the Khmer Rouge. All received foreign financial and military support. In June 1982, these groups formed the Coalition Government of Democratic Kampuchea (CGDK) with Sihanouk as president and Son Sann as prime minister. The alliance was uneasy and largely ineffectual, receiving little support from Cambodians inside the country, yet the UN recognized it as Cambodia's government.
The Path to Peace (1987-1991)
The political stalemate began to crack in the late 1980s due to changing global conditions. Soviet leader Mikhail Gorbachev's reforms (glasnost and perestroika) and the Soviet withdrawal from Afghanistan signaled a broader shift in Cold War dynamics. Vietnam's economy was in shambles by 1990, and Hanoi could no longer afford to support substantial forces in Cambodia. International pressure, the economic boycott led by the United States, and reduced Soviet aid all contributed to Vietnam's decision to withdraw.
Equally important, Cambodians began taking control of their own fate. Between December 1987 and July 1989, Prince Sihanouk and Hun Sen met on five occasions. These meetings transformed the Cambodian problem from an international proxy war into a civil conflict requiring a Cambodian political settlement. External powers were now confined to endorsing and guaranteeing solutions rather than dictating them. The Association of Southeast Asian Nations, particularly Singapore and Thailand, played crucial diplomatic roles in keeping the Cambodia issue alive internationally and facilitating negotiations.
Vietnam completed its military withdrawal from Cambodia in September 1989. Approximately 23,000 Vietnamese soldiers had been killed during the decade-long occupation. Over the next two years, intensive diplomatic efforts led to the Second International Conference on Cambodia in Paris. On October 23, 1991, the four Cambodian factions and eighteen foreign ministers signed the Paris Peace Agreements, establishing a permanent ceasefire and creating the framework for UN-supervised elections.
The PRK period demonstrates the complex aftermath of genocide. Liberation from the Khmer Rouge required Vietnamese intervention, yet that intervention created a new set of problems: occupation, international isolation, and prolonged civil war. Recovery occurred, yet remained constrained by embargo and continued conflict. Peace required not just local negotiations between Cambodians but also fundamental shifts in global politics. The period's legacy continues to shape Cambodia today, particularly in the enduring power of Hun Sen and the Cambodian People's Party, whose origins lie in these years of Vietnamese-backed rule.