As President Trump has noted, the world has a real problem: NK, which will dominate the entirety of his trip, not just the first half, as this article claims.

NK reiterated yesterday that it has no interest whatsoever in diplomacy;  SK IC believes it likely that NK will test a missile and a bomb during Trump's visit.

That kind of provocation could conceivably spark a response, especially if it is a H-bomb in the Pacific and/or it kills people, as it might well do if it is a missile test.

With 3 carrier battle groups close to NK and F-35s now stationed on Kadena, the US is preparing to use the military option.

Essentially, NK and the US are on the brink.  NK refuses to give up its WMDs;  the US insists that they must. The PRC does not want to press sufficiently to force NK's denuclearization and Russia claims that sanctions will never lead to NK's denuclearization.

Thus, the options are:

a) horrific war in Korea;

b) even worse possibility of NK thermonuclear ICBMs hitting the US.