The U.S. and its allies have confirmed that North Korea has tested a nuclear weapon in the northern part of the country. Calling it a defense against invasion, the rest of the world looks warily on believing a nuclear North Korea puts other nations -- particularly those geographically close -- at risk. One Asian expert and UAB history professor, Dr. John Van Sant, tells WBHM's Steve Chiotakis that what complicates a diplomatic resolution is the history of bad blood - not only with the U.S., but with North Korea's neighbors.