I highly doubt they'll do anything. Then again, I wouldn't put it completely past them. The North Korean society, from what I know, is one of honor and respect. I heard from some source that they (the US) think North Korea's leader Kim Jung-Un is merely showing that if necessary he will do what he needs to do for his country. Another theory is that he was being looked down upon by his peers that are in high authority positions and he has to prove himself. Now on to the topic of actual warfare. I think it's ludacris at best if they were to launch a nuclear attack anywhere around them. Their best missle deployment system will only have about a 1800 mile radius, which although close, I don't think will touch any of the United States. Due to that they only have South Korea, Japan, China, and the wastelands of Russia to attack. With the anti-missle system that have been deployed around the area the nuke's target would doubtfully get touched. If they were to attack South Korea it wouldn't be the best for them for multiple reasons. A large percentage of their GDP would be taken out since they trade with South Korea as one of their primary trades and it would also be an act of war with most of the World. Since the United States is large allies with South Korea, the US will wage war on North Korea and since the United States has so many allies itself, it's close allies and even some distant will see the need to exterminate the threat. With Korea having limited at best allies, their chances of actually winning the war is slim to none. So basically, if they do decide to do anything rash like target the surrounding countries, they'd be metaphorically committing suicide.