North Korea's "Dear Leader," Kim Jong-il, has been dead for more than a year, but his policies live on under his son, Kim Jong-un. Despite cosmetic changes—an attractive first lady carrying a designer purse—economic reform appears to remain mostly talk and political adjustments only affect the internal balance of power. Now the "Great Successor" is continuing his father's policy of provocation, threatening to stage another nuclear test.
Although Pyongyang gave no specifics on its planned test, mid-February seems likely. That would mark Kim Jong-il's birthday and preempt the inauguration of Park Geun-hye as South Korea's new president.
Of course, the DPRK believes there never is a moment when it is not appropriate to increase tensions on the peninsula. And North Korean foreign policy is based on provocation.