This could become a very serious topic. It seems to me that POTUS has a limited range of options. His primary aim will be to negate the real threat with minimum US (his) loss. Secondary is minimum collateral (some of his), and tertiary losses (not his) are the lowest priority. However, POTUS can only act pre-emptively if his actions can perfectly decapitate the NK chain of command, with very limited losses on all sides. All other scenarios require POTUS to lose the initiative by waiting for the NK first strike so that, whatever the consequences, all losses are blamed on NK. Unfortunately, $64,000 question is, is POTUS a gambler? I don't think he is at heart and, I suspect he will play a waiting game with either: China doing the dirty work (that they should have done decades ago) or, staying ready and waiting for that NK pre-emptive that will hopefully be bungled and give POTUS the moral high ground (in a terrible mess).
OAP