First of all, Kimmy J would use a nuke with full repercussions intended.
Big Kim J would not play around with just antagonizing the west nor Trump.
When the day comes for K J to act, he will do exactly that.
If and when K J has the ability to nuke a western foe, he will do so with a missile and a live nuke attached.
And most likely several, not just the one.
So what would Donald do?
It would look like something between a nasty 5am tweet to a full blown WW III scenario.
The real question here is what would the Soviets do? China do?
Those that would have the "real" power to retaliate against the free world.
Would Putin look at this as his opportunity? China look at this as their opportunity?
While things appear relativety peaceful between the Soviets, China and the west we have to remember there is an all out desire for China and or the Soviets to advance into the slot of leader of the free world.
Which, wouldn't remain free for very long.
If Kim J and N Korea should test the west by taking out Hawaii or some other western territory using a nuke(s), and remembering how 9/11 so turned upside down western civilization and still is to this day, to not think the Soviets or China would not immediately poise themselves to take over the role of would leadership at any cost would be foolish thinking.
That is where WW III comes in.
The US would be damaged to great extent. Not only physically but more so psychologically.
The Soviets and China would need to fight it out between themselves until one emerges the victor.
Let the nukes fly...
With the spoils of western civilization the grand prize.
And all the while back here in the good ole US of A we would have the insanity of a Caesar-istic like president to worry and wonder about.
Would he retreat to the basement of Trump Tower? Or simply climb aboard one of his jets and fly away.