Lets put it this way. Kim Jong-un would be obliterated. The US would likely not go for an all out nuclear attack, but Kim Jong-un would not be their leader anymore. Kim Jong-un is just trying to talk tough to look like a powerful leader. At least through his generals. It's all bluff. I guess it's one way for North Korea to not have a dictator anymore. I wouldn't want to see it happen. It would be better if his people ended the dynasty themselves.