I think people are over-inflating the extent to which the North Korean government is as a threat to regional peace. The North Koreans have threatened to end the armistice before, and have cut off the hotline twice. The regime, while not the most rational bunch in the world, bases all of it's actions around one thing: maintaining the power of the regime. Attacking their Southern neighbors will end their sovereignty, because it will result in an invasion by the United States. In this way, they're less of a nuclear threat than Iran

 If anything occurs, it will be aimed at undermining American and South Korean military and political power; the shelling of the border island or the sinking of Pohang class corvette are recent examples of this. The North Koreans think they can get away with more because our military budget is being cut, that's all. They're testing the waters, seeing how much they can get away with in a region where American hegemony is on the decline. 

 This isn't to say that we shouldn't beef up regional security, the N Koreans aren't the apex of international rationality, and their actions can be hard to predict. Obviously, we should stay on high alert in case anything happens. I've been copy pasting my posts left and right because I don't feel like retyping them XD