Given that their window of opportunity is something less than 48 hours (best case) if the open with a nuke, and 5 days if they don’t (again, best case), they would have to give launch authority to the peons with the weapons to ensure a command could be issued (first thing the US does is destroy command and communication, air supremacy follows that afternoon).
Any attack will bring the instant death of the command structure - if they have any kind of political control over the nukes, they have to figure that political structure will be gone before they got to the “retaliatory” strike.
Besides, if you wait, you’re radar is ash, what are you going to aim at? All you are sure you know is still where it was last time you heard, are population centers Why wait to hit those?