So, if this war starts, are we gonna take off the kiddie gloves and really pound the shit out of them with no regard for civilian lives?
Nope. It will be a mass number of guided surgical strikes to annihilate their military and industrial assets, but some care will be taken to avoid excessive civilian casualties, although of course some will be inevitable.
I doubt the US would even retaliate with nukes if it were nuked by NK.