Sum of All Fears...

[The Duke]

There is only one circumstance I can envision where I would do it, as a retaliation.  I would have to, since deterrence depends upon it, and in the future, no one would take deterrence seriously if I didn't.

[The Duke]

My assumption is that neither Russia nor Cina would launch an attack, after all, we aren't going to fight Russia, and if we fought China over Taiwan, we'd be in a defensive war.  China would never be in a position where they'd feel a need to launch a nuclear attack evene if defeated, because there is no immediate threat to their existence.  So, yes, I assume we are really dealing with rogue states only.