Except that deterrence does not really work. There are weapons out there who are in the hands of people you do not control, and who knows, one day they may turn out crazy and launch a nuclear strike on the US. And because of their condition, they won't care less about total annihilation (they'll be safely in a bunker anyway) of their country and citizens as long as they can harm your country.
So, deterrence only works if your opponent has something TO LOSE. That's the whole concept, and the limits of the concept. That's why people get nervous about North Korea (and their elite who lets their own people starve to death), no matter how many nukes you have in your backyard to deter them from doing anything. There are some cases where it won't work.
PS: during the Cuba crisis, some nuclear russian submarines were THAT close to launching a strike on the US (2 of the 3 people in place were in favor of doing it until the 3rd one managed to calm them down), and they were sensible people who knew very well what it would mean for their mother country as well in terms of retaliation. Again. Deterrence is really a weak theory.