Vietnam invades Cambodia, December 1978

H1 History - syllabus 8838, 2027

What this lesson teaches

  • I can judge which factors shaped the Second and Third Indochina Wars.

    Syllabus 8838, Theme III, Learning Outcomes. evaluate the factors that shaped the development of Cold War conflicts in Southeast Asia

Make a guess

In December 1978 Vietnam invaded Democratic Kampuchea. How long do you think the Khmer Rouge government lasted?

  1. It survived, and Vietnam's army was driven back.
  2. About two weeks: Phnom Penh fell on 7 January 1979.
  3. About a year, after hard fighting for each province.
Show the answer

About two weeks: Phnom Penh fell on 7 January 1979.

Vietnamese forces swept in fast and installed Heng Samrin's government. But their troops then stayed for about ten years.

Vietnam overthrew the Khmer Rouge in two weeks and installed a friendly government, starting a decade of occupation.

On 25 December 1978, Vietnamese forces invaded Democratic Kampuchea. Phnom Penh fell on 7 January 1979.

Vietnam installed the People's Republic of Kampuchea under Heng Samrin, a former Khmer Rouge commander who had fled to Vietnam. About 150,000 to 200,000 Vietnamese troops stayed to support it.

The Khmer Rouge retreated to the Thai border and fought a guerrilla war. Many countries, including ASEAN, condemned the invasion as a violation of sovereignty, even though the Khmer Rouge regime had committed mass atrocities.

The occupation became a central issue in Southeast Asia for the next decade. It tested the principle that states should not use force against their neighbours.

Invasion
25 December 1978.
Phnom Penh falls
7 January 1979.
Vietnamese troops
About 150,000-200,000 stayed in Cambodia.

Real examples to use

UN seat

The General Assembly kept recognising Democratic Kampuchea, not the Vietnamese-installed government, year after year in the 1980s.

K5 plan, mid-1980s

The Vietnamese-backed government used forced labour to build defences along the Thai border, which made the occupation hated.

Worked example: Sovereignty versus humanitarian outcome

Why did ASEAN condemn the invasion despite the Khmer Rouge's crimes?

  1. Principle: invading a neighbour broke the rule of non-interference.
  2. Precedent: if accepted, it could threaten other small states.
  3. Security: Thailand now faced Vietnamese troops on its border.
  4. Result: ASEAN led the diplomatic campaign against the occupation.

Watch out for this

Vietnam withdrew from Cambodia soon after removing Pol Pot.

Vietnamese troops stayed for about a decade, until September 1989.

Check your understanding

Who led the government installed by Vietnam in 1979?

  1. Sihanouk
  2. Heng Samrin
  3. Pol Pot
Show the answer

Heng Samrin

Right. He led the People's Republic of Kampuchea.

Sources and context

Background reading for this chapter.

  • A CIA assessment of the conflict

    Paraphrase of the key judgments of an Interagency Intelligence Memorandum, "Sino-Soviet Competition in Indochina", prepared in the CIA, 14 November 1978.

  • A State Department analysis of Vietnam's motives

    Paraphrase of a briefing memorandum from the Acting Director of the Bureau of Intelligence and Research to Secretary of State Vance, 8 January 1979, the day after Phnom Penh fell.

  • Thailand watches the Vietnamese advance

    Paraphrase of a telegram from the US embassy in Bangkok to the State Department, 4 January 1979.

  • China prepares to attack

    Paraphrase of the minutes of a US National Security Council meeting on the Sino-Vietnamese conflict, 16 February 1979.

  • Lee Kuan Yew writes to Carter

    Paraphrase of a letter from Singapore's Prime Minister Lee Kuan Yew to President Carter, 1 March 1979.

  • a Vietnamese diplomat explains the Soviet treaty, November 1978

    Extract from the US record of a meeting in New York, 30 November 1978, between US official Robert Oakley and the Vietnamese representative (named "Co" in the record) in talks on normalising US-Vietnamese relations, four weeks after Vietnam signed its treaty with the USSR. Secret. Foreign Relations of the United States, 1977-1980, volume XXII, document 33. A US government document in the public domain.

  • Deng Xiaoping briefs President Carter, 29 January 1979

    Extract from the US memorandum of conversation of a meeting between President Carter, Vice Premier Deng Xiaoping and their senior advisers, Washington, 29 January 1979, a month after Vietnam invaded Cambodia. Foreign Relations of the United States, 1977-1980, volume XIII, document 205. A US government document in the public domain.

  • Carter reports Deng's private message, 30 January 1979

    Extract from a US memorandum of conversation, Washington, 30 January 1979, in which President Carter reported to his advisers on his private talk with Deng Xiaoping. China attacked Vietnam on 17 February 1979. Foreign Relations of the United States, 1977-1980, volume XIII, document 207. A US government document in the public domain.

  • the UN General Assembly on Kampuchea, November 1979

    Extract from United Nations General Assembly Resolution 34/22, "The situation in Kampuchea", adopted at the 67th plenary meeting, 14 November 1979, on a draft sponsored by the ASEAN states. A UN record.

  • a cartoon about the conflict, 1979

    An original cartoon drawn for these notes in the style of a Southeast Asian newspaper cartoon of 1979, after the Vietnamese invasion of Cambodia and the Chinese attack on Vietnam. It is not a copy of a real cartoon.

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