Kim Jong Un is building a nuclear missile that can reach the U.S. Can he be stopped? Here's everything you need to know: What's North Korea's goal?The tyrannical Kim dynasty has been pursuing nuclear weapons since the end of the Korean War. The current leader's father, Kim Jong Il, made the nuclear program the centerpiece of his regime's identity, to rally the starving, isolated country around a nationalistic goal and to extort aid from worried Western nations.