There is always that "what if" scenario that nobody considers at first...
Should we not expect the unexpected? What if they have somebody supporting them (i.e. China, Iran), any others? Whether it be with military force or financially, support is support. Pretty much every country dislikes the United States, you take your pick. I'm certain if they come at us alone they will be making the biggest mistake in the history of their country. But if not, that's a whole other situation.
I'm skeptical to believe that little Korean guy hasn't considered what he is up against. It doesn't make sense to attack us alone, so I am considering he has support of some kind which boosted his ego enough to threaten us. Hopefully he's just stupid and I'm wrong, but if I'm right, god help us... It could lead to another World War.