There is a power play going on within North Korea. They may want to move up in the world of politics and influence, but they won't want to risk destroying all life on earth just to advance those goals. They would have to be much more desperate for that to happen.
North Korea will not be nuking the United States. They are all bark and no bite. The threats don't mean anything at this point because if they truly wanted to nuke us they would have done it by now. The united states has nothing to be worried about in this situation.
North Korea has been making empty threats for the longest time ever. They're not that stupid as to nuke the U.S. and risk the entire world attacking North Korea at the same time. They know it, and so do we. Kim-Jong Un isn't going to risk his cushy position by doing something so stupid.
I don't feel leaders here would let it get to that point. I also think it would take a couple of absolutely insane leaders in North Korea to actually go through with something like that. North Korean leaders may believe they need nuclear weapon technology for leverage in dealing with the rest of the world or perhaps for defense against us. They're nuts, but probably not that nuts.