Every so often North Korea does something - usually not good that gets people's attention, otherwise they're ignored completely. This time North Korea REALLY wanted attention, one nuke and 6 missile tests later, here we are.
Not as often North Korea also likes to essentially threaten war - this time it disregards the 1953 armistice and threatened "nuclear war" for even any minor incidents. (right) This is the first time in a little while that North Korea has freaked out this much but there are some interesting theories.
One of the most interesting I've heard has to do with the president, Kim Jung Il. Since his apparent stroke the "dear leader" has been in declining health. One theory is that Kim is in dire health and essentially making a distraction for transfer of power or a distraction for infighting due to the transfer of power.
It's all speculation, but certainly interesting because of the apparent randomness of the latest North Korean freak out. Of course the worrying part is if the truth is something close to that, the normally crazy (but rational) leadership could do things it normally wouldn't.
But as I've heard a few say on TV. It's completely understanding why the US/SK military has upped it's alert level, but in reality North Korea does what it does best - blow smoke.