11. Concerns About Chinese Intervention Kept the US From Invading North Vietnam
The plans for invading North Vietnam were drawn only fifteen years after the Korean War. In that conflict, US and allied forces had pursued the routed North Koreans all the way to the Chinese border, based on the mistaken belief that China would do nothing. That led to the unpleasant surprise of the Chinese jumping in and pushing American forces all the way back to South Korea.
If China directly joined the Vietnam War in response to an American invasion of North Vietnam, things could easily escalate from there into WWIII, with the Soviets getting dragged in. Unlike the situation during the Korean War, the US no longer held an overwhelming nuclear superiority: by the second half of the 1960s, the Soviets possessed thousands of nuclear warheads and the means of delivering them to targets in the US. American interests in Vietnam were deemed not worth the risk, and thus the planned invasion of Hanoi-Haiphong was shelved.
