Iran, it appears, also paid Pyongyang for building the Deir al-Zor reactor in the Syrian desert, which bore striking similarities to the reactor in Yongbyon in North Korea. Ten North Koreans were reportedly killed by the Israeli air force when it bombed the site in September 2007. The North’s total annual take from nukes and missiles looks like it is about $3 billion, a figure more than a tenth of the country’s gross domestic product. The Kim regime, in part due to the failure of its internal economy, has become the world’s arch nuclear proliferator and a major seller of chemical weapons, such as those used by Syria’s Bashar al-Assad this past half-decade.

And the importance of this trade to the regime means that Pyongyang will continue to develop and test nuclear warheads, long-range missiles and assorted weaponry, thereby further undermining the world’s nonproliferation regime. No outsider can draw a straight line from infighting between the military and Kim Jong-un; to the execution of Jang Song-thaek; to deteriorating relations with Beijing; to the faltering economy; to weapons sales to Iran and others. Nonetheless, the purges and executions in North Korea look like they are pushing Kim and his ruling group in exceedingly dangerous directions. The Democratic People’s Republic of Korea has a history of surprising its neighbors and the United States. Add the element of a highly unstable political system, and there could be extremely unpalatable consequences.

Gordon G. Chang is the author of Nuclear Showdown: North Korea Takes On the World. Follow him on Twitter @GordonGChang.

Image: Flickr/Tormod Sandtorv.