Why did not USA bring cold war mentality to north vietnam?

Therefore southern vietnam get along with north vietnam? Is it because that is only one country that defeat USA, In spite of that was the same cruel with russia that USA accuse of it. Will korea unite in this model?
Why did not USA bring cold war mentality to north vietnam?
Why did not USA bring cold war mentality to north vietnam?
Why did not USA bring cold war mentality to north vietnam?
Why did not USA bring cold war mentality to north vietnam?
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