Perhaps related to the discussion started by Jerry69. I recall the Ford administration's response to the "axe murder incident" was a rather large show of force that had a similar "calming effect" on the North Korean regime.
Then again, there is a fairly large list of North Korean actions: https://fas.org/sgp/crs/row/RL30004.pdf

Although many people may believe Trump is calling the North Korean bluff of threatening a preemptive strike on US interests, everything I know about Trump makes me believe it is more likely that he simply does not care about other people dying, because he will be safe, and he will be allowed to use the military in a new war that he will most likely "win". But I suppose it doesn't really matter if North Korea does back down.

If.