. . . allied status hegemony in both countries is huge.  The South is saying it has veto power over military action on the Penninsula - because it means catastrophic loss to its population the moment war breaks out.  

Japan isn't going to stand with the US if Trump makes it a proxy war ground.

So, now, the US starts talking "defensive" positioning.  

Trump's ego and bombast led him to make threats the world (and his own advisors) are not willing to back up.  NK is discovering, if not KNOWS that.

This end up being a big loss for the US, the UN, "the West", one way or another.

Two options:  Military action on the Penninsula (with the only "lucky" outcome being a bomb hitting Jong Un and his generals directly and NK surrender); or, fully Nuclearized NK by virtue of its simply standing off against US (Trump) threats.

That is stacking up to be the only two options, and that will be the lesson the world learns.

What will the world do in response?