Cambodian–Vietnamese War

• 1. Introduction

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  The Cambodian-Vietnamese War began on the 25th of December 1978, when 150,000 Vietnamese troops crossed into Cambodia and dismantled a government in just two weeks. That government, the Khmer Rouge, had in the preceding years killed between 1.2 and 2.8 million of its own people - between 13 and 30 percent of Cambodia's entire population. The Vietnamese invasion ended those killings. Yet it also triggered a decade of occupation, a proxy war fed by Cold War rivalries, and an international diplomatic crisis that would leave Vietnam isolated from most of the world. How did two communist states that had fought side by side end up in open war? Who was pulling the strings behind them? And what did it take, after ten years of occupation and 15,000 Vietnamese soldiers killed, for Cambodia to find its way to any kind of peace?

• 2. Ideological Fractures

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  The Khmer Rouge took its name from a term applied to members of the Communist Party of Kampuchea, a party that had its origins in a split from a Vietnamese-dominated Indochinese Communist Party. That split carried lasting resentment. In 1941, the man known as Ho Chi Minh founded the Viet Minh to fight French colonial rule, and Vietnamese communists subsequently made extensive use of Cambodian territory throughout both the First Indochina War and later the Vietnam War. The Cambodian communists were never fully equal partners. In 1954, under the Geneva Accords, the Vietnamese signed agreements on behalf of Cambodian communists without their consent - agreements that denied those Cambodians any share of power in their own country.

  Pol Pot, who led the Khmer Rouge from 1963, harbored a deep fear that the Vietnamese wanted to create an Indochinese federation dominated by Hanoi. He also nursed irredentist ambitions over the Mekong Delta, which Cambodia had lost to Vietnam in previous centuries. The Khmer Rouge's ideological distance from Hanoi widened further with its embrace of a Maoist nationalism at the time of the Sino-Soviet split - a stance that put it closer to Beijing and in direct tension with a Vietnamese party aligned with Moscow.

  By 1974, clashes between Vietnamese communist forces and Khmer Rouge units had already begun even while both were fighting anti-communist governments in their own countries. The following year, Pol Pot signed a treaty of friendship with China - a signal of where his loyalties lay long before either side took power.

• 3. Years of Border Blood

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  On the 1st of May 1975 - barely 24 hours after the fall of Saigon - the Kampuchean Revolutionary Army invaded the Vietnamese island of Phu Quoc, claiming it was historically part of Kampuchea's territory. Nine days later, on the 10th of May 1975, KRA forces captured the Tho Chu Islands, where they executed 500 Vietnamese civilians. Vietnam pushed back, recaptured the islands, and even seized the Kampuchean island of Koh Poulo Wai before returning it to Kampuchea in August 1975 as a gesture toward diplomacy.

  Throughout 1976, both governments exchanged congratulatory messages and diplomatic visits while privately plotting against each other. On Phnom Penh Radio, broadcasts proclaimed the "militant solidarity and friendship" between the two states. Behind the scenes, Pol Pot's government was purging Vietnamese-trained personnel from its own ranks and making preparations for war.

  On the 30th of April 1977, the second anniversary of the fall of Saigon, Kampuchean forces attacked the Vietnamese provinces of An Giang and Chau Doc, killing hundreds of civilians. By September 1977, six divisions of the KRA had advanced roughly 10 kilometres into Tay Ninh Province, killing more than 1,000 Vietnamese civilians in Tan Bien district alone. Vietnam assembled eight divisions of an estimated 60,000 soldiers in response and crossed the border in December 1977. By the end of that month, Vietnamese formations had marched through Svay Rieng Province and stopped just short of the provincial capital. Khmer Rouge leader Khieu Samphan declared on the 31st of December 1977 that his government would sever diplomatic relations with Vietnam until Vietnamese troops left what he called the "sacred territory of Democratic Kampuchea".

  When Vietnamese forces withdrew in January 1978, having failed to force negotiations, the Khmer Rouge declared a great victory. Then, in April 1978, two KRA divisions massacred over 3,000 Vietnamese civilians in the village of Ba Chuc in An Giang Province.

• 4. The Invasion Itself

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  By the second half of 1978, Vietnam's Communist Party Politburo had concluded that the Khmer Rouge government was effectively a Chinese proxy, and that only conventional military force could remove it. On the 3rd of November 1978, Vietnam and the Soviet Union signed a Treaty of Friendship and Cooperation, which guaranteed Vietnam Soviet military aid if China intervened. The Vietnamese government then drafted 350,000 men into the military and deployed ten divisions along the border provinces of Long An, Dong Thap and Tay Ninh.

  On the ground, the balance of forces was lopsided. Vietnam in 1977 had an estimated 615,000 soldiers, 900 tanks, and 300 combat aircraft including a squadron of light bombers, supported by a 12,000-member air force. Kampuchea had an army of 70,000, only a few heavy tanks, 200 armoured vehicles, and limited air capability. Kampuchean leaders dismissed the gap, claiming that one Kampuchean soldier equalled 30 Vietnamese, and that with two million soldiers from a population of eight million they could "wipe out Vietnam's population of 50 million and still have six million people left". In reality, Cambodia's population was physically and mentally exhausted from years of forced labour, starvation and disease.

  On the 25th of December 1978, the full-scale invasion began with 13 divisions. Kampuchea's decision to fight conventionally cost it half its army in two weeks. On the 7th of January 1979, the People's Army of Vietnam entered Phnom Penh alongside members of the Kampuchean United Front for National Salvation. The following day, the pro-Vietnamese People's Republic of Kampuchea was proclaimed, with Heng Samrin as Chief of State. Heng Samrin had formerly commanded the Khmer Rouge's 4th Division before defecting to Vietnam.

• 5. Cold War Crossfire

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  China invaded Vietnam on the 17th of February 1979, aiming to capture the capitals of its border provinces and force a Vietnamese withdrawal from Cambodia. After three weeks, Chinese forces captured Cao Bang and Lao Cai; Lang Son fell after a month. China then announced it would not advance further. Vietnam's politburo had already ordered general mobilisation and was planning full conscription.

  Singapore's prime minister Lee Kuan Yew later wrote, in 2000, that the Western press had written off the Chinese action as a failure, but that he believed it changed the history of East Asia. Former US secretary of state Henry Kissinger wrote that China had succeeded in exposing the limits of Soviet strategic reach, and speculated that the Soviet desire to compensate for their apparent ineffectuality contributed to the decision to intervene in Afghanistan a year later.

  At the United Nations, the dynamics were equally tangled. Seven non-aligned members of the Security Council put forward a draft resolution calling for a ceasefire and the withdrawal of all foreign forces from Kampuchea. China, France, Norway, Portugal, the United States and the United Kingdom endorsed it. The Soviet Union and Czechoslovakia blocked it. The deposed Khmer Rouge government retained its UN seat. By January 1980, nearly 80 countries still recognised the legitimacy of Democratic Kampuchea, while only 29 had established diplomatic relations with the Vietnamese-installed People's Republic of Kampuchea.

  From the Western perspective and that of the Association of Southeast Asian Nations, the issue was Vietnamese aggression, not Khmer Rouge atrocities. Thailand, sharing an 800-kilometre border with Kampuchea, demanded immediate Vietnamese withdrawal. The British Army's Special Air Service trained resistance groups operating out of Thailand throughout the conflict. Romania was the only country in the Eastern Bloc that refused to recognise the new PRK government; Nicolae Ceausescu had warned Le Duan before the invasion that Vietnam would lose international support the moment it crossed the border.

• 6. Occupation and Resistance

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  On the 8th of January 1979, as the People's Republic of Kampuchea was established in Phnom Penh, the Khmer Rouge retreated into the jungle near the Thai border. The Thai government under Kriangsak Chamanan sheltered them at Khao Larn camp in Trat Province, in exchange for a promise from Deng Xiaoping to end Chinese support for Thailand's own communist insurgents.

  Opposition to the Vietnamese presence was not the sole territory of the Khmer Rouge. In October 1979, former prime minister Son Sann formed the Khmer People's National Liberation Front, a right-wing pro-Western organisation that at its peak fielded between 12,000 and 15,000 fighters. Former king Norodom Sihanouk led FUNCINPEC, formed after he had severed ties with the Khmer Rouge following his representation of them at the Security Council. Sihanouk called publicly for the UN General Assembly to expel Khmer Rouge representatives for their crimes and criticised ASEAN for enabling Chinese arms shipments to the group through Thai territory.

  By 1982, pressure from ASEAN had pushed all three factions toward an alliance. In December 1981, the Khmer Rouge formally abandoned Marxism-Leninism, adopting democratic socialism under a renamed party to make the coalition more palatable. On the 22nd of June 1982, leaders of the three organisations signed a Thai-sponsored agreement establishing the Coalition Government of Democratic Kampuchea, with Sihanouk as president, Khieu Samphan as vice-president in charge of foreign affairs, and Son Sann as prime minister.

  Inside Cambodia, Vietnamese occupation left its own marks. In 1986, there was one Vietnamese adviser for every Kampuchean cabinet minister and one for each of their three deputy ministers; final decisions by Kampuchean ministers required approval from those advisers. To strengthen the Cambodian-Thai border under the K5 Plan, the PRK conscripted 380,000 people, with large numbers succumbing to malaria. Claude Malhuret of Medecins Sans Frontieres reported that food from international relief organisations was withheld from areas under Khmer Rouge control, and that thousands of tons of aid spoiled on the docks of Kompong Som while food intended for the population was diverted to Vietnamese troops.

• 7. Withdrawal and Peace

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  Vietnam entered the 1980s maintaining the fifth-largest armed forces in the world, with 1.26 million regular soldiers under arms - 180,000 of them stationed in Cambodia in 1984. Military spending consumed one-third of the national budget, even as the Soviet Union provided US$1.2 billion in military aid annually. Japan suspended all economic aid to Vietnam in 1979. The United States convinced other UN members to block Vietnam from major international financial institutions, including the World Bank, the Asian Development Bank and the International Monetary Fund.

  In 1986, the Soviet government under Mikhail Gorbachev announced reductions in aid to friendly nations. For Vietnam, that meant losing 20 percent of its economic aid and one-third of its military aid. That same year, the Vietnamese Communist Party held its sixth National Party Congress, at which newly appointed General Secretary Nguyen Van Linh introduced the reform program known as Doi Moi - a Vietnamese term meaning renovation. Vietnamese leaders concluded that Doi Moi could only succeed if Vietnam ended its international isolation, and that isolation traced directly to the 1978 invasion.

  In June 1987, the Vietnamese Politburo adopted Resolution No. 2, calling for the complete withdrawal of Vietnamese soldiers from international duties and a reduction of 600,000 soldiers from army rolls. Then, on the 13th of May 1988, Resolution No. 13 on foreign policy set out to diversify and multilateralise Vietnam's foreign relations, end embargoes, and attract foreign investment. Vietnam ceased to classify the United States as a long-term enemy and China as an imminent danger.

  Between April and July 1989-24,000 Vietnamese soldiers returned home. Between the 21st and the 26th of September 1989, the remaining 26,000 Vietnamese soldiers were pulled out, officially ending a ten-year occupation that had cost Vietnam 15,000 soldiers killed and another 30,000 wounded. In May 1993, Sihanouk's FUNCINPEC movement defeated the Cambodian People's Party in general elections; when the CPP threatened secession of the eastern provinces, FUNCINPEC leader Norodom Ranariddh agreed to form a coalition government. The constitutional monarchy was restored shortly afterward, and the Khmer Rouge was outlawed by the newly formed Cambodian government.