North Korea has a long, long history of being obnoxious. Long time observers have noted that threats, bluster, and even occasional small scale military action against South Korea have been (rather successful) negotiating tools of the Nork regime.
I have to concur with this assessment. What is happening right now in North Korea has more to do with North Korean internal politics than what the North Korean government may feel towards the U.S., South Korea, or anyone else. But this is why the situation is dangerous. Osama Bin Laden felt that the only way that he could defeat the Saudi Royal family was to drag the U.S. into a shooting war against him …. hence 9/11. There may be some in North Korea who may feel that the only way to keep their grip on power is to instigate a conflict with South Korean and the U.S. …. hence all the talk of war and threats of nuclear attack. This is all just speculation, but I do know that when people in absolute power feel that their status is being threatened …. they are capable of anything. In the case of North Korea …. they are truly the last “Stalinist” regime …. and they all know that.
Galrahn at Information Dissemination has a great piece on the North Korean situation, escalation control/crisis management and seapower. He’s gotten a few technical details about Ballistic Missile Defense wrong, but his overall piece is informative, and thought provoking. It’s a long piece, but well worth your time. The comments are good too, especially for clarifying some of the BMD details.