The Nuclear Taboo
The need to preserve alliances was a compelling reason not to use nuclear weapons in Vietnam.
Why did the US not use nuclear weapons in Vietnam? We often assume that it was the doctrine of Mutually Assured Destruction that kept both superpowers from ever using them. But intelligence reports from the period paint a more nuanced picture, one where global abhorrence of nuclear weapons, or the ‘nuclear taboo’, made their use politically untenable.
In 1966, China began amassing forces in North Vietnam. Uncomfortable with the recent US involvement, by 1967 they would deploy 170,000 troops. US leaders in turn began to worry that China might invade South Vietnam if the North were threatened, as they had in the Korean War 16 years earlier. One possible route to stopping a repeat of Korea was using nuclear weapons against the Chinese and North Vietnam.