Kim Jong-un’s decision to take out his half-brother Kim Jong-nam, with the assassins using an internationally banned chemical agent to do it, is not the usual mode of operation for North Korea’s first family. While the Kims of Pyongyang have not hesitated to purge hundreds by some of the most draconian methods possible, they’ve been more reluctant to slay those who share the “sacred” baekdu bloodline that descends from the dynasty’s sire, Kim Il-sung. Both Kim Jong-un’s father and grandfather also had difficulties with troublesome brothers. They chose, however, to sideline or exile these recalcitrant siblings rather than murder them gangland style. The fact that Kim Jong-un was willing to risk even further international condemnation and isolation by eliminating his already-marginalized playboy half-brother suggests that his hold on power in Pyongyang might not be as airtight as many outsiders assume.

The founding father of North Korea, Kim Il-sung, faced his own sibling rivalry. Kim Yong-ju, who is assumed still alive at the advanced age of 96, was a rising star in his elder brother’s court, holding key positions in the Korean Workers’ party in the 1960s and early 1970s. He was even once thought to be his brother’s likely successor. Kim Il-sung passed him over as heir apparent, however, in favor of his son Kim Jong-il. The Russian-educated Kim Yong-ju had reportedly opposed the personality cult developing around his older brother, while Kim Jong-il enthusiastically promoted it. In 1975, Yong-ju was sent into internal exile, placed under house arrest in remote Jagang Province and not heard of again for almost two decades. He was brought back to Pyongyang by Kim Il-sung in 1993, the year before the dictator’s death. Still, being purged and internally exiled was far preferable to Kim Jong-nam’s fate of having poison rubbed in his face. Yong-ju continues to hold the position of honorary vice president of the Presidium of the Supreme People’s Assembly.