South Korea has managed to foil an apparent plot to kill the most prominent North Korean defector within its borders. Two North Korean army majors attempted to "defect" in order to get close to Hwang Jang Yop, the former chief ideologue of North Korea. They have beefed up security around him (from 8 around the clock guards to at least 10).
The most vital piece of information here is that Yop defected 13 years ago. It seems that North Korea is upping the ante considerably in recent weeks, between the naval confrontation, the reports of a nuclear test, and now this. Thinking more on the nuclear test, it is possible that the regime is trying to bolster its domestic legitimacy (in desperate tatters after the botched revaluation of the currency and attempt to shut down the black markets). The only legitimacy it has left comes from confrontation with outsiders.
Of course, it could be coincidence. This is not the first time North Korea has tried to kill Yop. If that is the case, however, the North Korean government is either incompetently walled off from itself (with the left hand not knowing what the right is doing) or else just oblivious to how it is viewed from outside.
Either way, I don't think this means that we have to worry about a war breaking out, yet, but it definitely means that the chances (in the sense meant by Schelling) are increasing.