This is just my opinion...
I don't think that North Korea will nuke us, I wouldn't put it past them to try to start a war though. Their leader would have to know he would be completely decimated, however the U.S. has a habbit of helping a country to rebuild that we devistated by war.
http://chartercities.org/images/14.jpg
This night time satellite view should help explain why they would want to start a war to rebuild.