Yeah, "This is it, boys." Maybe. North Korea screams threats, POTUS blusters back -- and suddenly, he's the bad guy. Or perhaps just a Nixionian pseudo-madman, inadvertently or not.
The thing is, for all his flaws, what better sort of background than President Trump's ought a fellow to have in order to understand the mind of a pampered, overfed autocrat with demonstrably bad taste? This may be the one thing about which he is outstandingly a subject matter expert -- but don't expect him to get any credit for it.
It's another "crisis" the world will muddle though, probably with far more ink, paper and whizzing electrons than any splash of nuclear fire. Kim Jong-un's military is remarkable for poor marksmanship and the DPRK is unlikely to be able to bluff their way out of a live-fire miss as a "warning shot." Therefore, I don't expect them to shoot at all.