By 1978 Indochina had split into camps, with the USSR backing Vietnam and China backing Democratic Kampuchea.
After 1975, Vietnam leaned towards the USSR, which could provide more aid. In June 1978 Vietnam joined Comecon, the Soviet-led economic bloc. On 3 November 1978, it signed a Treaty of Friendship and Cooperation with the USSR.
China saw this as Soviet encirclement. It already had Soviet forces to its north; now it had a Soviet ally to its south. China backed Democratic Kampuchea as a buffer and sent it advisers and aid.
Relations between Vietnam and China collapsed in 1978. Vietnam pressured its ethnic Chinese population, and around 250,000 fled to China. China cut all aid to Vietnam.
The USA chose China. Talks on normalising US-Vietnam relations stalled in 1978, while the USA normalised relations with China on 1 January 1979. A CIA assessment in November 1978 described the conflict as rooted in the clashing ambitions of China and Vietnam, each wanting paramount influence in Indochina.
- Comecon
- Vietnam joined in June 1978.
- Soviet-Vietnamese treaty
- 3 November 1978.
- Ethnic Chinese exodus
- Around 250,000 fled to China in 1978.
- US-China normalisation
- 1 January 1979.
Worked example: Tracing the camps
Explain how the Cold War divided Indochina by 1978.
- USSR and Vietnam: Comecon in June and the treaty in November 1978.
- China and Democratic Kampuchea: aid and advisers.
- USA and China: normalisation in January 1979.
- Result: a local conflict became part of the Sino-Soviet rivalry.
Watch out for this
The Third Indochina War was simply a proxy war between the superpowers.
Great-power rivalry shaped it, but Vietnam, Democratic Kampuchea and China pursued their own aims. China, not the USA, was Vietnam's main opponent.
Check your understanding
Why did the Soviet-Vietnamese treaty of November 1978 alarm China?
- China saw itself as encircled by the USSR and its ally.
- China wanted to join the treaty.
- It returned Taiwan to Vietnam.