On this day in 1979, 250,000 Chinese troops supported by 200 tanks invaded Vietnam. To hold off the Chinese, Hanoi marshalled 150,000 local militia and border guards who employed guerrilla tactics. After 27 days of fighting, approximately 60,000 Chinese soldiers and 20,000 Vietnamese were killed. China claimed victory but were repulsed and fled the county.
Beijing claimed the attack was being carried out against its former ally to protect ethnic Chinese from persecution at the hands of the government in Hanoi. In reality, the incursion was intended to pressure Vietnam to abandon its occupation of nearby Cambodia. China also wanted to send a message to the Soviet Union — Vietnam’s closest strategic partner — to stay out of Southeast Asia.
Cambodia, a Chinese ally, was ruled by Marxist-Leninist Pol Pot who’s regime killed up to 2 million or a quarter of its own population pursuing a complete egalitarian policy in which money was abolished and all citizens were made to wear the same black clothing. Mass killings of perceived government opponents then followed coupled with malnutrition and poor medical care.
Fearing the escalation of a large-scaled war with the Chinese, the Soviet Union did not provide military support to their Vietnamese ally.