That's a long way from the popular perception that "Uncle Jang" was nurturing his nephew as a regent appointed by Kim Jong Il. Jang was seen prominently behind Kim Jong Un as he walked beside his father's hearse during his 2011 funeral. He was also a fixture at the new leader's side as he toured the country.
The KCNA report was unusually specific in its accusations. It criticized Jang for not rising and applauding his nephew's appointment to a senior position because Jang "thought that if Kim Jong Un's base and system for leading the army were consolidated, this would lay a stumbling block in the way of grabbing the power."
It stressed repeatedly that Jang had tried to assemble a faction of his own, suggesting the purging process could still be playing out.
Jang's death could herald a "reign of terror," including more purges, said Lim Eul Chul, a North Korea expert at South Korea's Kyungnam University.
Another question mark is how the purge will affect North Korea's relationship with its only major ally, China. Jang had been seen as the leading supporter of Chinese-style economic reforms and an important link between Pyongyang and Beijing. China has called Jang's execution a domestic issue and has avoided further public comment.
North Korea has recently turned to attempts at diplomacy with South Korea and the United States. But tensions have remained high since Pyongyang's threats in March and April, which included warnings that it would restart nuclear bomb fuel production.
Another resident of Pyongyang, Ri Chol Ho, said he did not believe Jang alone was deserving of the harshest punishment.
"For this group of traitors who were going to destroy our single-hearted unity, execution is too lenient," he said. "They should be torn up and thrown into the rubbish bin of history."
Klug reported from Seoul. Associated Press writers Hyung-jin Kim and Eun-young Jeong in Seoul and Ken Moritsugu in Tokyo contributed to this report.