Yeah. Washington DC doesn't have some magic key that is the only thing that can launch or detonate US nuclear weapons. All the US executive branch has are codes that the nuclear weapons armed crews of the US military use to confirm orders are legitimate. All of those crews are able to launch or detonate their weapons. This is necessary because when the US military goes to a high defcon level, if the US nuclear command and the executive branch become unresponsive, doctrine calls for local commanders to start launching nuclear weapons without orders on the assumption a decapitation strike has been made against the US. Russia and the UK also have similar fail-deadly nuclear doctrines.

I kind of hope, perhaps naively, that because the US military generally does take self-preservation and safety somewhat seriously, especially in terms of the big stuff like nuclear, that the actual steps to targeting US territory and then actually launching the nuke on US territory, would have several "I'm not launching the first nuke on US citizens" types to stand in the way. There's even already a historical precedent for refusing to launch nukes on US citizens. I'd like to think, in the case of internal political instability, most launch sites and non-national guard bases will focus on keeping civilians away and telling dumbass governors to fuck off.