Third Indochina War: A Visual History

The Third Indochina War (1978-1991) began when Vietnam, provoked by Khmer Rouge border massacres, invaded Cambodia on 25 December 1978 and took Phnom Penh on 7 January 1979, ending Pol Pot's genocide and installing a client government. China, the Khmer Rouge's patron, invaded northern Vietnam in February-March 1979 to 'teach it a lesson' and withdrew after a month of heavy losses on both sides; Sino-Vietnamese border clashes continued through the 1980s. Vietnam occupied Cambodia for a decade against a Khmer Rouge-led coalition backed by China, Thailand, ASEAN and the West, and withdrew in 1989. The Paris Peace Agreements of October 1991 brought UN administration and elections in Cambodia and Sino-Vietnamese normalisation.

When it was fought: the era ribbon

The bold bar is Third Indochina War. The lighter bars are empires and wars from the same era and the same part of the world. Click any bar to jump to its page.

Vietnamese troops in Cambodia

Timeline of the Third Indochina War

1. 1977
   Khmer Rouge border attacks
2. 1978
   Vietnam invades Cambodia25 December.
3. 1979
   Phnom Penh falls; Sino-Vietnamese WarJanuary to March.
4. 1982
   Coalition Government of Democratic Kampuchea formed
5. 1984
   Laoshan fighting; K5 plan
6. 1989
   Vietnamese withdrawal
7. 1991
   Paris Peace Agreements; Sino-Vietnamese normalisation
8. 1993
   UNTAC elections

Vietnam invades Cambodia

The Khmer Rouge, allied to China and hostile to Hanoi, raided across the border in 1977-1978, killing thousands of Vietnamese villagers at Ba Chuc and elsewhere. Vietnam signed a treaty with Moscow and struck on Christmas Day 1978 with 150,000 troops; Phnom Penh fell in two weeks, revealing the killing fields, and the People's Republic of Kampuchea was proclaimed under defectors including Hun Sen. The Khmer Rouge fled to the Thai border and famine followed.

China's lesson

Deng Xiaoping, weeks after visiting Washington, sent some 200,000 troops into Vietnam's northern provinces on 17 February 1979. Vietnamese militia and border forces fought hard; the Chinese took Lang Son, Cao Bang and Lao Cai at heavy cost, declared their aim achieved and withdrew by 16 March, razing towns as they went. Both sides claimed victory; the war exposed the PLA's weakness and led to its modernisation. Artillery duels and battles for hills like Laoshan continued until 1990.

Occupation, K5 and Paris

Vietnam kept 180,000 troops in Cambodia fighting the Khmer Rouge and the smaller Sihanoukist and KPNLF forces from Thai border camps; the UN seat stayed with the ousted Khmer Rouge coalition. The PRK's K5 plan of forced labour on border defences killed thousands. Gorbachev's cuts to aid and the cost of isolation led Vietnam to withdraw by September 1989; Hun Sen and Sihanouk negotiated, and the Paris Agreements of 23 October 1991 created UNTAC, which ran elections in 1993. The Khmer Rouge boycotted them and disintegrated by 1998; China and Vietnam normalised relations in November 1991.

Related empires and wars

Chosen automatically by overlap in time and geography, plus a few hand picked connections.

Empires of the same era and region

• Khmer Empire (802 to 1431)
• Soviet Union (USSR) (1922 to 1991)
• British Empire (1583 to 1997)
• Third Portuguese Empire (1822 to 1999)
• Second French colonial empire (1830 to 1980)
• Spanish Empire (1492 to 1976)

Wars of the same era and region

• Vietnam War (1955 to 1975)
• Cambodian Civil War (1967 to 1975)
• Cold War (1947 to 1991)
• First Indochina War (1946 to 1954)
• Chinese Civil War (1927 to 1949)
• Myanmar conflict (1948 to present)

8 surprising things about the Third Indochina War

1. It was the first war between communist states, and the Sino-Vietnamese conflict the first between two nuclear-armed neighbours' allies to turn hot.
2. Vietnam ended the Khmer Rouge genocide and was punished for it with a decade of Western and Chinese isolation.
3. The Khmer Rouge kept Cambodia's UN seat until 1991 with US and Chinese support because Vietnam was Soviet-backed.
4. Deng Xiaoping told President Carter of the planned attack on Vietnam during his US visit in January 1979.
5. China's 1979 offensive lasted 27 days; Chinese casualties are estimated at 20,000 to 60,000.
6. The Thai border camps held over 300,000 Cambodian refugees for a decade.
7. UNTAC was the UN's largest and costliest peacekeeping operation to that date, at 2 billion dollars.
8. Hun Sen, installed by Vietnam in 1979, ruled Cambodia until 2023 and handed power to his son.

Sources

• Cambodian-Vietnamese War Wikipedia
• Sino-Vietnamese War Wikipedia
• Cambodia: Vietnamese intervention Encyclopaedia Britannica
• Nayan Chanda, Brother Enemy: The War after the War (1986) Harcourt Brace Jovanovich

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