North Korean scholars have come to expect the unexpected.

Even so, few analysts predicted North Korea's dramatic Friday the 13th announcement that it had executed Jang Song Thaek, the country's de facto No. 2 leader and uncle of Kim Jong Un.

The announcement of Mr. Jang's purge earlier in the week, itself unusual, had certainly put that possibility in play. But no one foresaw the public nature of the execution, complete with pictures of Mr. Jang being hauled before a tribunal, which was particularly jarring for the grim glimpse it offered of deep division at the highest levels of power in Pyongyang.

Nor did they foresee the 2,700-word laundry list of Mr. Jang's alleged crimes, from plotting a military coup to disrespecting a marble carving of Mr. Kim's signature and failing to clap wholeheartedly upon hearing news of his promotion.

Taken together, most North Korea watchers have agreed on at least this much: the past week's events have dragged North Korea into new and uncertain territory.