NEW YORK — Today, on the second anniversary of Kim Jong-il’s death, only two of the seven officials who walked alongside his hearse at the state funeral, and his heir, Kim Jong-un, remain. Five have been stripped of their titles, sent to labor camps, or executed — as in the case of Jang Song-thaek.

Mr. Jang had been seen as the No. 2 wielder of power in North Korea in recent years and as a top henchman of both the Great Leader, Kim Il-sung, his father-in-law, and of the Dear Leader, Kim Jong-il, his brother-in-law, for the past four decades. The news that he was executed on Thursday, for plotting a military coup against his nephew, the new Dear Leader, Kim Jong-un, is exceptional and especially frightening since he was a member (by marriage) of the Kim family.

During that snowy winter two years ago when Kim Jong-il died, I was living in the suburbs of Pyongyang, the North Korean capital, for almost six months. I remember vividly the bone-aching chill of the Siberian winds, as well as the abruptness with which the news of the death was told to us. I was teaching English on an official exchange in a locked compound, guarded by armed soldiers. That year, all the universities around the country were shut down in preparation for the regime change, and students had been sent to the fields to build their “prosperous nation,” but the 270 sons of the elite, 19 and 20 years old, had been sent to this fortified campus to wait out an impending political storm.

My students, sons of the elite, worshipped the Dear Leader, but on occasions, they had already begun mentioning their “Daejang-nim,” or “general,” referring to Kim Jong-un. They swore to loyally assist the young man — about whom not much was known — because he would surely continue to build, as his grandfather and father had done, their prosperous nation....