North Korea executed Jang Song Thaek, who was not only the uncle of leader Kim Jong Un but also viewed by some as the second-most powerful man in the secretive and isolated country.
North Korea's official news agency said Jang was plotting to overthrow Kim Jong Un, often referred to in official releases as the supreme leader. It also accused him of wanting to become premier and of criminal acts including womanizing, drug abuse and mismanaging the financial system.
Jang was married to Kim Jong Un's paternal aunt; he was believed to be 67 years old, according to a Reuters report. He was a vice chairman of the National Defense Commission and part of the ruling Workers' Party politburo.
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There may indeed have been a coup plot, said Colin Chapman, president of the Australian Institute of International Affairs, a think tank.
"When you do this, it's probably quite successful as Kim Jong Un flexing his muscles and saying 'I'm the boss here. I'm not having my wicked uncle plotting with the Chinese to get rid of me,'" he told CNBC.
But others aren't certain there was a plot. There isn't any direct evidence, said Andrew Gilholm, head of Asia analysis at Control Risks, a global risk consultancy.
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While some may point to a recent spate of defections from North Korea as an indication a plot was afoot, "people close to Jang Song Thaek know what a purge looks like and it would be normal for them to get out the country," he told CNBC.
While the execution may lead to awkward family dinners, it isn't clear what the move means for politics in the secretive and poverty stricken regime.
"There are a few ways people have tried to spin this: one, it means Kim Jong Un is weak and was facing a challenge and that's why he executed Jang. Or (two) Kim Jong Un is strong because he was able to purge Jang. He's going to throw off the shackles of Kim Jong Il's regency and going to rule more independently," said Andrew Gilholm, head of Asia analysis at Control Risks, a global risk consultancy.
"I suspect it was the latter," he told CNBC. "He has the confidence to do his own thing."
Since taking power after his father died in 2011, Kim Jong Un has carried out a nuclear weapons test, at least two long-range rocket launches and continued a series of threats of missile strikes against the U.S. and South Korea.
Gilholm noted Kim Jong Un has now removed most of the people his father put in place to help him.
"It is strange to us. In North Korea, that's fairly normal. And not too dissimilar to what Kim Jong Il did when he took power," Gilholm said.
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After the execution, North Korea's relationship with China, its one major ally, could bear watching as well, Chapman said.
"The question to be asked is what are we going to see China do now," Chapman told CNBC. "They obviously thought they could use Kim's uncle to their advantage and they found out they can't."
Earlier this year, China signaled increasing irritation with its neighbor over its frequent threats of nuclear action. It is unlikely however that Beijing will take any action which would collapse North Korea's government, amid concerns it could spur a wave of refugees.
—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1