North Korea once again has made a move against the rest of the world, specifically the U.S. and South Korea. While technically still at war, North and South Korea have not had open conflict in many years due to an agreement that was titled the Non Aggression Act. Just recently, North Korea said that they were canceling the Non Aggression Act, which could mean war in the Korean Peninsula. But because North Korea does not have the strength to pose a major threat to the rest of the world, this is likely just a bluff.
Not only have they torn up the non-aggression act with South Korea, they have also threatened preemptive nuclear attack on the U.S. They made this claim right before the U.N. placed further restrictions on them. What the further restrictions will do to change North Korea's attitude is unknown; it could either make them change their policies to embrace more of a western ideal, or become more aggressive. However, the odds are that the restrictions won't change North Korea's attitude toward the rest of the world.
North Korea is still has quite a while to go before it will actually be a threat to the U.S. but the fact that some time in the future they may have the capabilities of shooting a nuclear missile at the U.S. is still something to be worried about.
It is unknown exactly what China will do, but they have made it quite clear that they want peace on the Korean Peninsula. China being North Korea's main ally will play a crucial role in deciding the fate of the Korean Peninsula.
It is unclear what North Korea is attempting to do here. Why North Korea would tell everyone they were canceling the Non Aggression Act is rather mysterious. If they were to go to war with South Korea it makes more sense for it to come completely out of nowhere. That way, they would have the element of surprise on their side. It may be that Kim Jong-Un is trying to show the world that he is a man to be feared, but he still knows he does not have the capability to face off against the Western World and her allies.