When Vietnam invaded Cambodia and overthrew Pol Pot, where they aware of the level of atrocities he was carrying out and did they have any humanitarian motivations?

While some broad strokes answers have highlighted some of the issues relating to this question, I feel the question itself – awareness of atrocities and the ‘humanitarian-ness’ – has not been answered.

So, firstly some context.

The prickly relationship between the two ‘hereditary enemies’, as alluded to by reference to the ‘don’t spill the master’s tea’ story that has been given in a previous response, was exacerbated by the relationship both the CPK (Communist Party of Kampuchea) and Hanoi had to maintain during the Vietnam War.

While the support of the North Vietnamese propped up the Khmer Rouge for years, after 1973 the Cambodian Communists began further splits from their Vietnamese ‘ally’. The Vietnamese aid to the Khmer Rouge dwindled and Pol Pot et al began arresting Khmer Viet Minh, executing some or removing them from positions of authority. In July 1973 a CPK congress decided that ‘in the future, Vietnam should be treated as a friend, but a friend with a conflict.’

China had given the Khmer Rouge significant support and this continued after the liberation of Phnom Penh in 1975. Relations between Hanoi and Beijing had cooled in the late 1960s, Cambodia was seen by the Chinese as a potential ally in keeping Soviet influence – via Vietnam – out of Asia. ‘In the end it was realpolitik far more than ideological affinity which brought China and Cambodia together.’

In July 1975, speaking about the Khmer Rouge victory, Pol Pot stated ‘In the entire world, no country, no people and no army has been able to drive the imperialists out to the last man and score total victory over them. Nobody!’ This is indicative of the kind of ‘denial’ that characterised the CPK. The Vietnamese had achieved a victory one hundred times more impressive, but it wasn’t mentioned. This is echoed in the date the leaders gave for the formation of the Cambodian communist party, 1960, rather than 1951 which would have acknowledged Vietnamese paternity.

So by 1976 the situation looks like this: Cambodia and Vietnam are ‘whole’ again, and Communist. Cambodia is reliant on Chinese support, while Vietnam on the USSR. China used Cambodia as a barrier to the spread of Vietnamese power.

1977 saw large border clashes between Cambodia and Vietnam. In September two Cambodian divisions massacred the village in Tay Ninh province leaving nearly 1000 dead.

By this time S-21 had seen thousands of Khmer Rouge cadre imprisoned and tortured due to their supposed links with Vietnam and accused of plotting a coup to replace the CPK leaders with a pro-Hanoi group. This would become an all out purge and perhaps 100 000 or 250 000 cadre would be executed. This was at the height of tensions with Vietnam and it had the effect of leaving Cambodia vulnerable, particularly in the Eastern Zones where Pol Pot had focused his paranoid suspicions (due to the proximity with Vietnam).

In public, the CPK leaders whipped up a frenzy of patriotic fervour against their hereditary enemy. In a speech for radio Phnom Penh we are given the outlandish plans for defeating the Vietnamese: “In terms of numbers, each one of us must kill 30 vietnamese … that is to say we lose one against 30. We will therefore need two million troops for 60 million Vietnamese. We need only two million troops to crush the 50 million Vietnamese and we will still have six million Cambodians left. We must formulate our combat line in this manner and implement the slogan of one against 30.”

On Christmas day, 1978, the Vietnamese invasion began and swiftly defeated the Khmer Rouge, who took their army and thousands of people with them into the North West and Thailand. January 7, 1979 is liberation day and marks 3 years, 8 months and 21 days of the Khmer Rouge regime coming to an end.

So I’ve given here a very brief overview of some of the key themes in the context of this conflict, now I want to address the actual questions at hand.

Were they aware of the atrocities? Yes. They had forced some refugees back into Cambodia who knew what the conditions were like. Cadre who defected to Vietnam had also told them about the policies the CPK had enacted. This is reflected in the propaganda that the Vietnamese spread in Cambodia that promised to give people back some autonomy and revive money, Buddhism etc.
Was it a humanitarian intervention? It is sometimes considered to be one. See for instance Gary Clintworth’s ‘Vietnam’s intervention in Cambodia in International Law’, which argues the case that it can be considered as such. Others are less convinced of the altruistic intent of the invasion. For instance, Philip Short in ‘Pol Pot’ writes:

“To the overwhelming majority of Cambodians in January 1979, the Vietnamese appeared as saviours. Hereditary enemies or not, Khmer Rouge rule had been so unspeakably awful that anything else had to be better. Vietnamese propagandists exploited this to the full. Vietnam’s army, they claimed, had entered Cambodia not to occupy it but to deliver the population from enslavement by a fascist, tyrannical regime which enforced genocidal policies through massacres and starvation. That was of course untrue. The Vietnamese leaders had not been bothered in the least by Khmer Rouge atrocities until they decided that Pol Pot’s regime was a threat to their own national interests.”

This is emphasised by the actions of the Vietnamese in the spring of 1979 when Phnom Penh was systematically looted and aid which was eventually delivered to the Cambodians by international organisations was also taken, in part, by Vietnam.

I think it is wise to assume a level of political realism in regard to the Vietnamese invasion of Cambodia that incorporates their national interest being the first and foremost goal.

- Short 'Pol Pot: History of a Nightmare' 2005,

- Heder 'Racism, Marxism, labelling and genocide in ben Kiernan's Pol Pot Regime' South east asia research 1997