How dangerous is North Korea?

Lieutenant-General HR McMaster is a serious-looking dude, and when he warns that North Korea is very dangerous you have to believe that he knows more about Kim Jong un's nuclear plans than the rest of us. So we should be alarmed. But let's see what Kim Jong un's intentions could be. So he's built for himself an intercontinenal ballistic missile that can reach some American cities, he has developed nuclear warheads that can probably be fitted to the missiles within the next year or so. But to what end? Is he seriously going to launch a nuclear ICBM and try and hit Chicago? What's the point? What will he get out of it? The chances are if it's just one ICBM, the US will be able to shoot it down with the interceptors based in Alaska or even the THAAD systems located in South Korea or the Standard SM-3 anti-missile interceptors on warships in the Asia-Pacific region. Either way, a North Korean nuclear attack on the United States is going to be met with an overwhelming response. That doesn't mean North Korea will be obliterated, but as in Iraq, everything of note will be targeted. Everything Kim has been developing to turn his country into a mini-superpower will be destroyed. If he then attacks South Korea, the retaliation will be even greater. Kim's regime will be over, finished. So it's one thing to be all big and brave and threaten to attack the United States with his biggest missiles but what does he think he's going to gain by actually launching one? Zero minus!!! So why does McMaster think Norh Korea is so dangerous that he feels the need to spell it out in public? What does he know that we don't know? Or is it a classic case of the old Donald Rumsfeld connundrum? McMaster knows what he knows but he doesn't know what he doesn't know. In other words, what Kim is actually going to do when he has a nuclear-tipped ICBM. Can the US risk doing nothing preemptively if there is a 60-40 chance that Kim will fire an ICBM towards the US? This is the real danger, not Kim having ICBMs but not knowing what's in his mind. It's the one thing that even the best intelligence services in the world can never be sure about. It's Kim's intentions that pose the biggest threat. If we could find out his game plan, then dealing with him would be easier. This is why McMaster is looking so grim these days. Whenever Trump asks him: "What is Kim going to do?", he has only one answer: "I don't know Mr President."