Story highlights The message: "Don't mess with Kim Jong Un," says North Korea expert Mike Chinoy

"This is a stunning development," says North Korea expert

Jang Song Thaek was married to Kim's aunt, was vice chairman of the top military body

An uncle of North Korean leader Kim Jong Un has been executed for trying to overthrow the government, the Korean Central News Agency reported early Friday.

"Traitor Jang Song Thaek Executed" blared the headline posted by the state-run news agency about the man who, until recently, had been regarded as the nation's second-most powerful figure.

The story said that a special military tribunal had been held Thursday against the "traitor for all ages," who was accused of trying to overthrow the state "by all sorts of intrigues and despicable methods."

It added, "All the crimes committed by the accused were proved in the course of hearing and were admitted by him."

Once his guilt was established, Jang was immediately executed, it said.

The KCNA report described Jang as "despicable human scum" and "worse than a dog," and said he had betrayed his party and leader.

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Photos: Photos: A glimpse inside North Korea Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – North Korean citizens bow before the portraits of the founding father Kim Il-Sung, left, and his son Kim Jong-Il, in Pyongyang, North Korea on Monday, April 9, 2012. April 15 marked the 100-year anniversary of the founder's birth and journalists were allowed inside the country. Hide Caption 1 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – North Korean technicians check the Unha-3 rocket at Tangachai-ri space center on Sunday, April 8. Hide Caption 2 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – A controller is seen from the window of a train along the railway on the west coast Sunday. A controversial missile launch is expected to take place in the coming days. Pyongyang insists it has no bad intentions and invited foreign journalists to view its launch site. Hide Caption 3 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – Citizens dance on Monday during a rehearsal for the commemoration of Kim Il-Sung's 100th birthday anniversary. Japan, the United States and South Korea see the launch -- which would violate U.N. Security Council resolutions -- as a cover for a long-range ballistic missile test. And a South Korean intelligence report says it's likely to precede a nuclear test, as it did in 2006 and 2009. Hide Caption 4 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – North Korean soldiers are seen from the window of a train along the railway heading from Pyongyang to the North Pyongan Province on the west coast. Hide Caption 5 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – A woman plays the piano and entertains in a downtown Pyongyang restaurant. U.S. President Obama said the real consequence for North Korea, should it go through with the launch, is that the country's leaders will miss an opportunity. "I hope that at some point the North Koreans make the decision that it is in their interests to figure out how to feed their people and improve their economy rather than have big parades where they show off weapons," he said in March. Hide Caption 6 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – Two women on the the train prepare food for the journalists traveling across the country. Hide Caption 7 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – The dress rehearsal for the celebration continues in the capital. Hide Caption 8 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – A pin with the face of Kim Il-Sung is affixed to the uniform of a North Korean soldier standing guard at the space center in Pyongyang on Wednesday, April 11. Hide Caption 9 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – A woman ties the branches of apple trees on a farm near Pyongyang on Tuesday, April 10. Hide Caption 10 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – Workers and farms are seen through the window of a train as it passes through the country. Hide Caption 11 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – Bicycles line the road as citizens work the land between Pyongyang and the North Phyongan province. Hide Caption 12 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – A North Korean soldier is seen from the window of a train as he walks near a small town along the railway heading from Pyongyang to the North Pyongan Province on the west coast. Hide Caption 13 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – Employees work in a textile factory in Pyongyang. Hide Caption 14 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – People line the street as they wait for a bus. Hide Caption 15 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – A dance troupe performs during the opening ceremony of the Spring Arts Festival in Pyongyang. Hide Caption 16 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – A band performs during the opening of the Spring Arts Festival. Hide Caption 17 of 18 Photos: Photos: A glimpse inside North Korea A glimpse inside North Korea – A building adorned with a huge portrait of the late president Kim Il-Sung is cleaned by workers in Pyongyang. Hide Caption 18 of 18

Photos: The photos N. Korea banned Photos: The photos N. Korea banned Photos North Korea didn't want you to see – A stern looking North Korean guard by the Chinese border customs office. This image was deleted by North Korean officials. Hide Caption 1 of 17 Photos: The photos N. Korea banned Deleting the offensive photos – Writer Johan Nylander and his guide, Ko Chang Ho, watch as a North Korean guard deletes 90 photos deemed unacceptable. Nylander was able to recover the photos with the help of an IT specialist -- the images that follow are an edited selection. Hide Caption 2 of 17 Photos: The photos N. Korea banned Hello, Dear Leader – This propaganda monument of "Dear Leader" Kim Jong-Il by a countryside road, not far from the border to China, was deleted by authorities. North Korea required images of leaders be full body shots. Hide Caption 3 of 17 Photos: The photos N. Korea banned Waiting for a train – People standing by the train track, while a guard is monitoring the bike race. Hide Caption 4 of 17 Photos: The photos N. Korea banned Watching the race – In the city of Rason, people are leaning out of windows to get a glimpse of the Western cyclists. Hide Caption 5 of 17 Photos: The photos N. Korea banned Pedestrian peasants – A woman and a man walking by the side of the road lined with cornfields. Hide Caption 6 of 17 Photos: The photos N. Korea banned Village life – Villagers waving by the race path. Hide Caption 7 of 17 Photos: The photos N. Korea banned Heavy security – Guards and custom officials by the border to China. Hide Caption 8 of 17 Photos: The photos N. Korea banned Secret volleyball court? – By the border checkpoint next to the Tumen River, North Korean customs officials can play volleyball. Officials prohibited any photos of North Korean military bases. Hide Caption 9 of 17 Photos: The photos N. Korea banned Photos North Korea didn't want you to see – Peasants and villagers standing by the road to look at the Western cyclists Hide Caption 10 of 17 Photos: The photos N. Korea banned Keeping watch – Guard keeping an eye on the bikers next to a small village. Hide Caption 11 of 17 Photos: The photos N. Korea banned Photos North Korea didn't want you to see – Kids playing outside village houses. Hide Caption 12 of 17 Photos: The photos N. Korea banned Waiting for the cyclists – Spectators waiting for the bikers to reach the finish line. In the background the "Great" and "Dear Leaders" Kim Il Sung and his son, Kim Jong-Il. Hide Caption 13 of 17 Photos: The photos N. Korea banned Standing on bikes to see cyclists – Huge crowds -- some of whom standing on their own bikes -- as they await cyclists by the race finish line in Rason. Hide Caption 14 of 17 Photos: The photos N. Korea banned Document check – Custom official and tourist bureau guide checking foreigners' passports. Hide Caption 15 of 17 Photos: The photos N. Korea banned Water checkpoint – Guides from the local tourist bureau handing out water bottles to bikers, monitored by a guard in the background. Hide Caption 16 of 17 Photos: The photos N. Korea banned Writer and his minder – Journalist Johan Nylander and his North Korean guide, Ko Chang Ho. EDITOR'S NOTE: This image was not among those deleted by North Korean officials. Hide Caption 17 of 17

Photos: Kim Jong Un and North Korea's military Photos: Kim Jong Un and North Korea's military North Korean leader Kim Jong Un meets with North Korea's first female fighter jet pilots in this undated photo released by the country's state media on Monday, June 22. He called the women "heroes of Korea" and "flowers of the sky." Hide Caption 1 of 55 Photos: Kim Jong Un and North Korea's military Kim stands on the snow-covered top of Mount Paektu in North Korea in a photo taken by North Korean newspaper Rodong Sinmun on April 18 and released the next day by South Korean news agency Yonhap. Kim scaled the country's highest mountain, North Korean state-run media reported, arriving at the summit to tell soldiers that the hike provides mental energy more powerful than nuclear weapons. Hide Caption 2 of 55 Photos: Kim Jong Un and North Korea's military Kim Jong Un, center, poses with soldiers on the snow-covered top of Mount Paektu in an April 18 photo released by South Korean news agency Yonhap. Hide Caption 3 of 55 Photos: Kim Jong Un and North Korea's military Kim visits the Kumsusan Palace of the Sun in Pyongyang, North Korea, on April 15 to celebrate the 103rd birth anniversary of his grandfather, North Korean founder Kim Il Sung. Hide Caption 4 of 55 Photos: Kim Jong Un and North Korea's military Kim inspects a drill for seizing an island at an undisclosed location in North Korea in an undated picture released by North Korea's official Korean Central News Agency on February 21. Hide Caption 5 of 55 Photos: Kim Jong Un and North Korea's military Kim speaks during a meeting of the Political Bureau of the Central Committee of the Workers' Party of Korea in Pyongyang, North Korea, in this photo released February 19 by the state-run Korean Central News Agency. Hide Caption 6 of 55 Photos: Kim Jong Un and North Korea's military A picture released by the North Korean Central News Agency shows North Korean leader Kim Jong Un appearing without his cane at an event with military commanders in Pyongyang on Tuesday, November 4. Kim, who recently disappeared from public view for about six weeks, had a cyst removed from his right ankle, a lawmaker told CNN. Hide Caption 7 of 55 Photos: Kim Jong Un and North Korea's military Kim is seen walking with a cane in this image released Thursday, October 30, by the state-run Korean Central News Agency. Hide Caption 8 of 55 Photos: Kim Jong Un and North Korea's military Kim sits in the pilot's seat of a fighter jet during the inspection. Hide Caption 9 of 55 Photos: Kim Jong Un and North Korea's military This undated photo, released Tuesday, October 14, by the KCNA, shows Kim inspecting a housing complex in Pyongyang, North Korea. International speculation about Kim went into overdrive after he failed to attend events on Friday, October 10, the 65th anniversary of the Workers' Party. He hadn't been seen in public since he reportedly attended a concert with his wife on September 3. Hide Caption 10 of 55 Photos: Kim Jong Un and North Korea's military A picture released by the KCNA shows Kim and his wife watching a performance by the Moranbong Band on Wednesday, September 3, in Pyongyang. Hide Caption 11 of 55 Photos: Kim Jong Un and North Korea's military Kim tours a front-line military unit in this image released Wednesday, July 16, by the KCNA. Hide Caption 12 of 55 Photos: Kim Jong Un and North Korea's military Kim poses for a photo as he oversees a tactical rocket-firing drill in June. Hide Caption 13 of 55 Photos: Kim Jong Un and North Korea's military Kim watches a tactical rocket-firing drill in June. Hide Caption 14 of 55 Photos: Kim Jong Un and North Korea's military A North Korean soldier patrols the bank of the Yalu River, which separates the North Korean town of Sinuiju from the Chinese border town of Dandong, on Saturday, April 26. Hide Caption 15 of 55 Photos: Kim Jong Un and North Korea's military In this photo released Thursday, April 24, by the Korean Central News Agency, Kim smiles with female soldiers after inspecting a rocket-launching drill at an undisclosed location. Hide Caption 16 of 55 Photos: Kim Jong Un and North Korea's military A picture released Tuesday, March 18, by the KCNA shows Kim attending a shooting practice at a military academy in Pyongyang. Hide Caption 17 of 55 Photos: Kim Jong Un and North Korea's military A North Korean soldier uses binoculars on Thursday, February 6, to look at South Korea from the border village of Panmunjom, which has separated the two Koreas since the Korean War. Hide Caption 18 of 55 Photos: Kim Jong Un and North Korea's military A North Korean soldier kicks a pole along the banks of the Yalu River on Tuesday, February 4. Hide Caption 19 of 55 Photos: Kim Jong Un and North Korea's military A photo released by the KCNA on Thursday, January 23, shows the North Korean leader inspecting an army unit during a winter drill. Hide Caption 20 of 55 Photos: Kim Jong Un and North Korea's military Kim inspects the command of an army unit in this undated photo released Sunday, January 12, by the KCNA. Hide Caption 21 of 55 Photos: Kim Jong Un and North Korea's military Kim visits an army unit in this undated photo. Hide Caption 22 of 55 Photos: Kim Jong Un and North Korea's military Kim inspects a military factory in this undated picture released by the KCNA in May 2013. Hide Caption 23 of 55 Photos: Kim Jong Un and North Korea's military Kim visits the Ministry of People's Security in 2013 as part of the country's May Day celebrations. Hide Caption 24 of 55 Photos: Kim Jong Un and North Korea's military A North Korean soldier, near Sinuiju, gestures to stop photographers from taking photos in April 2013. Hide Caption 25 of 55 Photos: Kim Jong Un and North Korea's military North Korean soldiers patrol near the Yalu River in April 2013. Hide Caption 26 of 55 Photos: Kim Jong Un and North Korea's military Kim is briefed by his generals in this undated photo. On the wall is a map titled "Plan for the strategic forces to target mainland U.S." Hide Caption 27 of 55 Photos: Kim Jong Un and North Korea's military Kim works during a briefing in this undated photo. Hide Caption 28 of 55 Photos: Kim Jong Un and North Korea's military In this KCNA photo, Kim inspects naval drills at an undisclosed location on North Korea's east coast in March 2013. Hide Caption 29 of 55 Photos: Kim Jong Un and North Korea's military Kim, with North Korean soldiers, makes his way to an observation post in March 2013. Hide Caption 30 of 55 Photos: Kim Jong Un and North Korea's military Kim uses a pair of binoculars to look south from the Jangjae Islet Defense Detachment, near South Korea's Taeyonphyong Island, in March 2013. Hide Caption 31 of 55 Photos: Kim Jong Un and North Korea's military Kim is greeted by a soldier's family as he inspects the Jangjae Islet Defense Detachment in March 2013. Hide Caption 32 of 55 Photos: Kim Jong Un and North Korea's military Kim is surrounded by soldiers during a visit to the Mu Islet Hero Defense Detachment, also near Taeyonphyong Island, in March 2013. Hide Caption 33 of 55 Photos: Kim Jong Un and North Korea's military Kim arrives at Jangjae Islet by boat to meet with soldiers of the Jangjae Islet Defense Detachment in March 2013. Hide Caption 34 of 55 Photos: Kim Jong Un and North Korea's military Soldiers in the North Korean army train at an undisclosed location in March 2013. Hide Caption 35 of 55 Photos: Kim Jong Un and North Korea's military In a photo released by the official North Korean news agency in December 2012, Kim celebrates a rocket's launch with staff from the satellite control center in Pyongyang. Hide Caption 36 of 55 Photos: Kim Jong Un and North Korea's military Kim, center, poses in this undated picture released by North Korea's official news agency in November 2012. Hide Caption 37 of 55 Photos: Kim Jong Un and North Korea's military Kim visits the Rungna People's Pleasure Ground, under construction in Pyongyang, in a photo released in July 2012 by the KCNA. Hide Caption 38 of 55 Photos: Kim Jong Un and North Korea's military A crowd watches as statues of North Korean founder Kim Il Sung and his son Kim Jong Il are unveiled during a ceremony in Pyongyang in April 2012. Hide Caption 39 of 55 Photos: Kim Jong Un and North Korea's military A North Korean soldier stands guard in front of an UNHA III rocket at the Tangachai-ri Space Center in April 2012. Hide Caption 40 of 55 Photos: Kim Jong Un and North Korea's military In April 2012, Pyongyang launched a long-range rocket that broke apart and fell into the sea. Here, the UNHA III rocket is pictured on its launch pad in Tang Chung Ri, North Korea. Hide Caption 41 of 55 Photos: Kim Jong Un and North Korea's military – A closer look at the UNHA III rocket on its launch pad in Tang Chung Ri, North Korea. Hide Caption 42 of 55 Photos: Kim Jong Un and North Korea's military A military vehicle participates in a parade in Pyongyang in April 2012. Hide Caption 43 of 55 Photos: Kim Jong Un and North Korea's military North Korean soldiers relax at the end of an official ceremony attended by leader Kim Jong Un at a stadium in Pyongyang in April 2012. Hide Caption 44 of 55 Photos: Kim Jong Un and North Korea's military Kim Jong Un applauds as he watches a military parade in Pyongyang in April 2012. Hide Caption 45 of 55 Photos: Kim Jong Un and North Korea's military A North Korean soldier stands on a balcony in Pyongyang in April 2012. Hide Caption 46 of 55 Photos: Kim Jong Un and North Korea's military North Korean soldiers march during a military parade in Pyongyang in April 2012. Hide Caption 47 of 55 Photos: Kim Jong Un and North Korea's military Soldiers board a bus outside a theater in Pyongyang in April 2012. Hide Caption 48 of 55 Photos: Kim Jong Un and North Korea's military North Korean performers sit below a screen showing images of leader Kim Jong Un in Pyongyang in April 2012. Hide Caption 49 of 55 Photos: Kim Jong Un and North Korea's military North Korean soldiers salute during a military parade in Pyongyang in April 2012. Hide Caption 50 of 55 Photos: Kim Jong Un and North Korea's military North Korean soldiers listen to a speech during an official ceremony attended by leader Kim Jong Un at a stadium in Pyongyang in April 2012. Hide Caption 51 of 55 Photos: Kim Jong Un and North Korea's military Members of a North Korean military band gather following an official ceremony at the Kim Il Sung stadium in Pyongyang in April 2012. Hide Caption 52 of 55 Photos: Kim Jong Un and North Korea's military North Korean military personnel watch a performance in Pyongyang in April 2012. Hide Caption 53 of 55 Photos: Kim Jong Un and North Korea's military A North Korean controller is seen along the railway line between the Pyongyang and North Pyongan provinces in April 2012. Hide Caption 54 of 55 Photos: Kim Jong Un and North Korea's military A North Korean military honor guard stands at attention at Pyongyang's airport in May 2001. Hide Caption 55 of 55

"This is a stunning development," Marcus Noland, a senior fellow at the Peterson Institute for International Economics, told CNN on Thursday. "I've been following North Korea for 20 years and I do not remember them ever publicly announcing the execution of a senior leader. You hear rumors about it, but this theatrical arrest earlier in the week and now this execution are unprecedented."

He added, "The regime, I think, is trying to intimidate anyone that might have independent ideas or harbor any ambitions."

KCNA's report comes days after Jang was removed from his military post

Jang, who was married to Kim's aunt, had served as vice chairman of North Korea's top military body and had often been pictured beside the 30-year-old leader, who has ruled North Korea since the death in 2011 of his father, Kim Jong Il.

It has previously been reported that Kim Il Sung -- the late father of Kim Jong Il and the architect of the North Korean state -- disapproved of Jang's marriage into the family, according to Time Magazine.

In Washington, a State Department official acknowledged having seen the report of Jang's execution. "While we cannot independently verify this development, we have no reason to doubt the official KCNA report," Deputy Spokeswoman Marie Harf said in a statement.

"If confirmed, this is another example of the extreme brutality of the North Korean regime. We are following developments in North Korea closely and consulting with our allies and partners in the region," Harf added.

"I think the message to people in North Korea is: Don't mess with Kim Jong Un," said Mike Chinoy, a senior fellow at the U.S.-China Institute at the University of Southern California and author of " Meltdown: The Inside Story of the North Korean Nuclear Crisis.

"This is about as brutal and ruthless a signal that could possibly be conveyed -- that Kim Jong Un is in charge and that anybody who seeks to create any kind of alternative power center is going to get destroyed politically and, in the case of Jang Song Thaek, physically as well."

He called the incident "the most dramatic, highly visible shakeup in the North Korean leadership in decades."

Kim accused Jang and his allies of double-dealing behind the scenes, "dreaming different dreams" and selling the country's resources at cheap prices, thereby threatening North Korea's economic development, according to a KCNA statement this week.

"Jang desperately worked to form a faction within the party by creating illusion about him and winning those weak in faith and flatterers to his side," the statement said.

The statement accused Jang of womanizing, drug use, gambling, eating at expensive restaurants and undergoing medical treatment in a foreign country.

Friday's KCNA report accused Jang of having distributed pornographic pictures among his confidants and having taken at least 4.6 million euros (US $6.3 million) "from his secret coffers and squandered it in 2009 alone."

Two allies of Jang -- Lee Yong-ha and Jang Soo-kee -- were recently executed, South Korean lawmakers told reporters prior to Friday's report.

The lawmakers, including Cho Won-jin of the governing Saenuri Party, said they had received a briefing from South Korea's National Intelligence Service. CNN has not been able to independently confirm the report.

North Korea, a state shrouded in secrecy, has been involved in a protracted standoff with its neighbors and Western powers over its nuclear weapons program.

Tensions between North Korea and South Korea soared this year as Pyongyang reacted angrily to tightened United Nations sanctions imposed in response to its latest nuclear test.

The two sides are still technically at war after the Korean conflict, which began in 1950 and ended in 1953 in a truce, not a treaty.

The South Korean government held a national security meeting on Friday morning and was keeping a close eye on events in the north, Unification Ministry spokesman Kim Eui-do told reporters.

On a separate note, Seoul has accepted a proposal from Pyongyang to meet on December 19 in the Kaesong North-South Korea Industrial Complex, the spokesman said.

The execution may have repercussions among the security and military forces as well as in the economy, since Jang was well-connected in those areas, USC's Chinoy said.

"All those people now are either going to have to make very visible that they're abandoning that previous connection and that they're going to show total loyalty to Kim Jong Un, or they're going to be in trouble."

But it's not clear what, if anything, the incident may portend, he added. "It raises a lot more questions than answers."

For example, the killing could affect Pyongyang's relationship with Beijing, since Jang had dealt extensively with China -- North Korea's biggest and most important neighbor and supplier of food and aid, said Chinoy, who was a CNN correspondent.

"I think the Chinese saw him as a sober, adult supervisor" of the untested young leader, he said. And Pyongyang's denunciation of Jang -- which implied he had had dubious connections with an outside power -- was likely referring to China, whose leaders may now be "deeply unsettled," Chinoy said.

The incident could have even wider repercussions, Chinoy said.

If there is a sense of instability inside North Korea, with top-level people getting killed and others at risk, "there's always the temptation to strike out externally," Chinoy said. "You can't rule that out."