A very worrisome sign’: North Korea executes uncle of leader Kim Jong Un

North Korea executes Kim Jong Un's uncle 2:09

Young North Korean leader Kim Jong Un's previously powerful uncle has been executed as a traitor, the country's state-run news service said Thursday. 

According to KCNA, the uncle, Jang Song Thaek, was guilty of "attempting to overthrow the state by all sorts of intrigues and despicable methods with a wild ambition to grab the supreme power of our party and state."

On Monday, the isolated regime announced that Jang had been dismissed from his vaunted official post for a string of criminal acts, including corruption, womanizing and drug-taking. 

Jang Song Thaek is dragged into court by uniformed personnel in this picture published in a North Korean newspaper. Rodong Sinmun - Yonhap via Reuters

"All the crimes committed by the accused were proved in the course of hearing and were admitted by him," KCNA stated on Thursday — in a report that claimed that "people throughout the country broke in to angry shouts" when they heard of Jang's alleged crimes.

The over-the-top report goes on to call Jang "despicable human scum."

South Korea's spy agency last week said it believed Jang, long regarded as the second most powerful man in the secretive state, had been relieved of his posts in November.

Some experts have said the moves indicate Pyongyang is undergoing its biggest leadership upheaval since the death in 2011 of former leader Kim Jong Il, the younger Kim's father.

A senior U.S. intelligence official tells NBC News that the U.S. has no reason to doubt that Jang was executed after a show trial on treason charges, but the U.S. has not yet independently confirmed the death.

The official said it is tough to read the rationale behind the execution but called it more likely a "power play" or "family dispute" rather than an ideological move where one side or the other represented reformist elements.

Jang was married to Kim's aunt, Kim Kyong Hui, the younger sister of Kim Jong Il.

Alexandre Monsourav, a specialist in North Korea at the U.S.–Korea Institute at Johns Hopkins’ School of Advanced International Studies, said Kim is sending a alarming message to the U.S.:

"Kim Jong Un is willing to kill his own blood. He’s showing that really he has no mercy or pity. To me it’s a very worrisome sign. You see these extremist actions, you really have to take it very seriously."

Monsourav added, "Whether it’s his young age or personal insecurity making him do this, we need to be very careful around him."

He said the uncle is "not a traitor."

"He was the guy who essentially challenged Kim Jong Un," said Monsourav. "He wanted to build his own dynasty and topple the king. He built a party above the party and a cabinet above the cabinet. So the kid saw it coming and decided to take action against him and extinguish all possible doubts among the population about who is in control."

Sung-Youn Lee, a Korean studies professor at Tufts University, said the escalation of brutality is not a threat to the U.S. but to those close to Jang.

"I don’t expect him to launch a war or anything. He’s not suicidal,” he said. "What I do expect to see is hundreds of others who were close to Jang rounded up and summarily executed or thrown into gulags."

Lee said the uncle has been viewed as the No. 2 for 10 years and considered himself a reformer who would eventually rule North Korea.

"He may have miscalculated and had an inflated sense of his own importance and a lot of flatterers around him."

Meanwhile, tensions are still high on the Korean Peninsula following a torrent of threats in March and April by Kim's government against Washington, Seoul and Tokyo, including vows of missile and nuclear strikes and warnings that Pyongyang would restart nuclear bomb fuel production.

The Associated Press contributed to this report