AP Photo

Recent intelligence, including images of activity around the Punggye-ri nuclear test site, suggests that North Korea may be preparing for its third nuclear weapon test.

Indeed, senior North Korean military leaders stated on 24 January that they were preparing a 'high-level' nuclear test in part as a reaction to recent UN sanctions in response to the December 2012 long-range rocket launch. These recent alarms are another episode in North Korean provocation: why would North Korea test and why now? What are the implications if North Korea does test? And what if it does not test?

Nuclear testing for technical reasons would be plausible given North Korea's history of failed missile and nuclear performances. North Korea first tested a nuclear device in 2006. However...