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.