This chapter recounts the Vietnam War in the context of the Sino-Soviet competition for leadership in the global communist movement. It shows that after Nikita Khrushchev’s fall from power in October 1964, the Soviet leadership sought to build up their own revolutionary legitimacy by supporting Hanoi’s war effort. The Chinese leaders resented Soviet involvement, and tried to dissuade North Vietnam from overdependence on Moscow. However, China’s descent into the chaos of the Cultural Revolution lessened Beijing’s leverage over North Vietnam. From the late 1960s, Hanoi increasingly began to tilt in the Soviet direction, beginning a geopolitical shift that would completely reshape the region in the coming years.

By the early 1960s, Vietnam was firmly lodged in China's embrace. Khrushchev's commitment to Vietnam was limited, as he focused instead on relations with the United States. However, after his ouster in October 1964, Khrushchev's successor, Leonid Brezhnev, began to see Vietnam as an opportunity to demonstrate Moscow's revolutionary leadership. The Soviet Union's support for Vietnam served two purposes: establishing credibility in the revolutionary world and asserting its position as America's equal. As the war escalated, both Moscow and Beijing's commitment to Vietnam grew. Despite disagreements over military tactics, the Soviets won Hanoi's loyalty, largely because they supplied Vietnam with badly needed military aid. Yet the end of the war became a Pyrrhic victory for the Soviets. Moscow ended up investing heavily in Vietnam's reconstruction and industrialization, which contributed to the Soviet Union's later insolvency. This chapter highlights the importance of understanding the Vietnam War not only as an East–West struggle but also as an East–East struggle, with the Soviet Union and China competing for power and influence across the region.