Even if DPRK drops a fission-fusion weapon in Mid-Pac, we will do nothing.
And in doing nothing in response to a live thermonuclear bomb test (except more jabber, letters of reprimand, etc), the US will immediately lose face with all Asian nations, inspire Iran to move against Israel (they are on the border now), and give Kim the green light to launch on any US city he chooses ...
Millions are going to die whatever course is taken here; its just a choice of are they Korean or American ...