There have been hints that a number of politicians who might have had to issue a retaliation order might have refused to do so from purely moral reasons.

In Richard Rhodes Arsenals of Folly a close adviser to Ronald Reagan is quoted as saying:

"I think deep down he doubted that he could bring himself to strike another country with [nuclear weapons]"

Somewhat to my surprise, I'm from the UK and was in my teens in the 1980s where Reagan wasn't exactly portrayed in a positive light, I've found myself believing that Reagan probably would have had the moral courage to do such a thing.