When Kim Jong Un became leader of North Korea in 2011, he was surrounded by advisers who were two and in some cases nearly three times his age. Most had decades of experience in the Workers’ Party or military. Two were members of Kim’s family.

But rather than lean on that support team, Kim has instead sought to dismantle it, using a string of demotions and purges to grab power almost solely for himself. On Friday, North Korea announced the execution of the most prominent of his advisers, his uncle Jang Song Thaek, accusing him of opposing Kim’s rise and plotting an overthrow.

The pace and brutality of Kim’s attempted consolidation of power far exceeds analysts’ predictions and carries significant consequences for the region and the United States. If Kim can indeed lock down power, one of the world’s most secretive and repressive nations may continue as it is for decades. If he fails, a 65-year run of family rule could face resistance, and his nuclear-armed nation could descend into chaos. [Read North Korea’s announcement of Jang’s execution.]

For now, there are no outward signs of instability in the North, and it is unclear whether Jang’s execution — documented on the front page of North Korea’s state-run newspaper — marks the last stage of Kim’s ascendance or the first hint of opposition. Some analysts see it as a Stalin-style warning to other potential rivals, those who think that Kim is either too untested or unqualified to run the country.

Kim is thought to be 30 years old, making him one of the world’s youngest heads of state. Some who study the North say that, because of his age, he has felt it necessary to quickly remove those older advisers who had been loyal to his father, Kim Jong Il. Well before Jang’s purge, Kim had ousted scores of second- and third-level functionaries in the Workers’ Party and the military — among the North’s biggest personnel turnovers in decades.

In a telltale sign of the change, Kim has removed or demoted five of the seven elderly officials who walked alongside the hearse at Kim Jong Il’s state funeral two years ago. Those officials, dubbed at the time the “Gang of Seven,” were described in the South Korean media as likely to form the backbone of Kim Jong Un’s rule. Several in the group had known Kim Jong Il, son of national founder Kim Il Sung and the country’s second head of state, from his college days or before. Their average age at the time of the funeral: 73.

Among the gang, U Tong Chuk, who oversaw the North’s secret police, has not been seen in public since March 2012, his absence unexplained. Ri Yong Ho, a high-ranking military chief, was relieved of his duties in July 2012 because of what the North tersely described as an illness. Two other top officials were demoted. Jang’s ouster was by far the most public. The only two who have kept their positions — Choe Tae Bok and Kim Ki Nam — are in their mid-80s and represent little threat.

“Kim Jong Un has proven to the nation and his people that he is capable of taking out even those closest to him,” said Suh Choo-suk, an expert at the Korea Institute for Defense Analyses in Seoul. Suh added that the turnover recalls the 1950s and ’60s, when Kim Il Sung purged a group of more moderate challengers with ties to the Soviets and Chinese. The founder banished or killed those opponents, replacing them with a handpicked group of former guerrillas who had fought alongside him in northeastern China.

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Even Kim Il Sung did not fully consolidate control until 1972 — 24 years after he established the country — when the North adopted a constitution authorizing his supreme power. His son and heir, Kim Jong Il, needed almost as much time to cement his own rise: He was groomed by Kim Il Sung starting in the mid-1970s and gained full control of every major institution in 1998, four years after his father’s death.

For Kim Jong Un, the father-to-son power transfer wasn’t nearly as well planned. When Kim Jong Il died in 2011, the succession process was just starting again and Kim Jong Un had not yet built up his own network of lieutenants.

As a result, many outside experts and U.S. officials thought that Jang and others — including Kim Jong Un’s aunt, Kim Kyong Hui — would play key caretaker roles, perhaps in a power-sharing system. That hasn’t happened. In the months after his father’s death, Kim Jong Un took on multiple and redundant leadership positions, placing him clearly in supreme command. Although Kim might still rely on his aunt for guidance, she is thought to suffer from liver problems and is rarely seen in public.

The effect of Kim freeing himself from his senior advisers remains uncertain. Several Beijing-based analysts and scholars said Friday that they feared that North Korea’s relations with China would suffer, as Jang had been a key interlocutor with Chinese officials. Other experts, such as Bruce Klingner, a senior research fellow at the Heritage Foundation, said Kim has no potential “moderating influence” and might behave more recklessly.

The execution of Jang has also sparked concern that Kim can act rashly, crossing lines that even his father and grandfather would not have traversed. Kim family members, for example, have been safe from execution for decades.

“The way Kim Jong Un dealt with his uncle was very cruel,” said Cheng Xiaohe, an expert in North Korean affairs at Renmin University’s School of International Studies in Beijing. “He utterly turned back on his own flesh and blood.”

Yoonjung Seo in Seoul and Guo Chen in Beijing contributed to this report.