North Korea's young leader promoted a new army marshal after sacking his top general in what a South Korean official report said was a bid to impose authority on a military that has been the backbone of his family's long rule over the isolated state.
But analysts said the moves, just seven months since rising to power, do not suggest any fundamental change by Kim Jong-un to the policies of his grandfather and father which have left North Korea constantly on the brink of famine and ostracized by the most of the world.
The rise of relative unknown Hyon Yong-chol to vice marshal was announced by North Korean state media on Tuesday.
Thought by South Korea's defense ministry to be in his early 60s, Hyon first rose to prominence in 2007. In 2010, he was named a "leader" along with then-heir apparent Kim Jong-un and his place in the ruling elite confirmed by being part of the official delegation at December's funeral of former ruler, and the young Kim's father, Kim Jong-il.
Generals in their 60s are considered young in North Korea, where remnants of the anti-Japanese struggle of the state's founder Kim Il-sung -- the new leader's grandfather -- who are in their 80s are still present in government and usually expected to die in uniform.
It was not known whether Hyon would replace Ri Yong-ho as head of the North Korean army, one of the world's largest.
An assessment of the changes by the South Korean government seen by Reuters, said that some 20 top officials had been purged since Kim Jong-un began his ascent to power in 2009.
"The purging of Ri could be a message towards the new military, as it remains a threat to the Kim Jong-un regime, although it served an important purpose in helping Kim to the throne," said the report on Ri's ousting.
Kim Jong-un, believed to be in his late 20s, has already stamped his image on North Korea, an impoverished nation with nuclear weapons ambitions and where a recent U.N. report said malnutrition stunts one in three children.
Partly educated in Switzerland and bearing a physical resemblance to his revered grandfather -- who is the North's eternal president -- the plump young leader has jollied up his and North Korea's image.
In sharp contrast to the austere, reclusive image of his father, state media has shown Kim visiting fun fairs, speaking in public and applauding at a rock concert at the weekend.
But he appears to have done little, if anything, to address the desperate economic situation he inherited from his father in a country where average incomes are estimated by South Korea at just $1,200 a year.
"Kim Jong-un is shuffling things to establish a system that fits his era and moving on from the transitional period that had been left over by his father," said Koh Yu-hwan, an expert on North Korea's ruling ideology at Dongguk University in Seoul.
"We will be seeing a lot of unknown characters in the era of Kim Jong-un."
ACCORDION PLAYING UNCLE CEMENTS HIS ROLE
One of the main beneficiaries of Vice Marshal Ri's ousting looks to be Jang Song-thaek, the young Kim's uncle who married into the ruling family and who is reckoned by many analysts as the real power behind the throne.
The South Korean government report said the 66-year old Jang and Choe Ryong-hae, a long-time party faithful used as a counterbalance to Jang's influence, were behind Ri's ouster.
The handsome, accordion-playing Jang has been a constant presence around Kim Jong-un. He overcome his own purge, bitter palace intrigue and personal tragedy to become the chief adviser to his nephew and the third Kim to lead North Korea.
People with knowledge of the North's leadership family have said aunt Kim Kyong-hui has struggled with bouts of alcoholism and was a peripheral figure. Choe is seen as a balance to Jang and Hyon will be an addition, experts say.
Given the closed nature of North Korea, one of the world's most secretive states, it is not possible to independently verify many of the views of observers.
Choe was First Secretary of the Central Committee of the Kim Il-sung Socialist Youth League, the main ruling party spin-off that trained young communists for leadership and a power base for Kim Jong-un.
"Previously there were two pillars in North Korea's regime -- the elite guardians' group led by Jang Song-thaek and Choe Ryong-hae and military elites' group led by Ri," said Lee Seung-yeol, researcher at Ewha Institute of Unification Studies.
"Now that Ri, whom Kim Jong-il wanted to face against Jang, was removed, the elite system built by Kim Jong-il has completely broken apart," he said.
(Additional reporting by Jack Kim, Christine Kim and Jumin Park, Editing by Jonathan Thatcher)