The US nearly lost the Korean war.
The US army was nearly overrun at least once.
The US airforce never achieved air superiority, and Soviet aircraft were better in most ways.
The only undisputed advantage the US had was nukes, which is why MacArthur wanted to use them tactically (!)
The only path that America had to win in Vietnam was to destroy it, including the population they were allegedly there to protect. Hence they lost.
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The US nearly lost the Korean war.
The US army was nearly overrun at least once.
The US airforce never achieved air superiority, and Soviet aircraft were better in most ways.
The only undisputed advantage the US had was nukes, which is why MacArthur wanted to use them tactically (!)