North Korea has been making headlines recently, mostly due to its nuclear weapons. In early January, the country’s leader, Kim Jong-un, boasted of his ability to reach the U.S. with nuclear-armed missiles. Then in March -- in an apparent 180 -- he told South Korean officials that he would be willing to negotiate with the U.S. to completely denuclearize. What are the rules that govern who has nukes and who doesn’t? And why do some countries maintain huge nuclear arsenals, while many other countries don’t have any nukes? Joe Hanson of It's OK to Be Smart joins host Myles Bess to investigate.