I really think this may in fact just be North Korea trying to get back onto the front pages of world newspapers.
"Previously, North Korea reportedly told U.S. negotiators in private talks that it had nuclear weapons and might test one of them."
http://www.msnbc.msn.com/id/6944560/
I guess we will have to see if N. Korea is "just bluffing"..
If they actually test a bomb, I would then say we are justified in taking them out.. with prejucice..