PRC support for North Korean military action is extremely unlikely. This has been less known for a few years, and widely known for much shorter ammount of time.
PRC is interested in earning money, that we have, and that they want from us. Good old capitalism (joke intended). China needs us to stay healthy consumers, and they can't do that if everyone gets nuked, and they're not gonna risk that for fattie-kim-un. They simply aren't.
So it is safe enough to remove PRC from this equation.
NK is most likely gonna focus its military effort on SK rather than American pacific posessions, since SK is their main priority. The "US Imperialist" rethoric they're so fond of is mostly just theatre, to boost morale among the population.
I agree NK is a danger. But I must insist that NK is mainly a danger to its immediate surroundings, not the whole world, and not to US mainland. If a nuclear missile launched from NK even hits Hawaii, I'm gonna be more surprised at the American failure to intercept it, than anything else.
And any conventional attack on American posessions in the Pacific, as a preemptive measure, so to invade SK with more ease... I mean, come on, you might just as well worry that Taliban will invade your mainland.
