Soviet nukes were not why the U.S. held back in Korea. It was the unpleasant prospect of a war with China (albeit a non-nuclear China).
https://www.airspacemag.com/military-aviation/how-korean-war...
And it didn't use them in Vietnam because it was thought to require so many (dozens/hundreds) as to be the antithesis of reunification.
---
In short, the US avoided nukes for decades in the hope of peace, not because there were any nukes sighted on D.C. (MAD).
Soviet nukes were not why the U.S. held back in Korea. It was the unpleasant prospect of a war with China (albeit a non-nuclear China).
https://www.airspacemag.com/military-aviation/how-korean-war...
And it didn't use them in Vietnam because it was thought to require so many (dozens/hundreds) as to be the antithesis of reunification.
---
In short, the US avoided nukes for decades in the hope of peace, not because there were any nukes sighted on D.C. (MAD).