"There'd be no reason for Kim Jong-un himself to dismantle after just seven months in office the support structure his father built for him," said Baek Seung-joo at the Korea Institute for Defense Analyses. "The shadow of Jang Song-taek looms large" over the young leader.

In January 2009, when Kim Jong-il handpicked his son Jong-un to succeed him, he handed control of the military to Ri, of the State Security Department to its first deputy director U Dong-chuk, and of the Workers Party's Organization and Guidance Department to some officials close to Jang, according to an informed source. But no sooner was Kim dead than Jang set about eliminating Ri, U and other key officials.

North Korea is now firmly under the control of Jang Song-taek, the eminence grise behind 20-something leader Kim Jong-un, following the purge of a rival group led by army chief Ri Yong-ho. Analysts say Jang has emerged as the sole power behind the throne, systematically dismantling a power structure put in place by former leader Kim Jong-il before his death in 2011.

Jang, who is Kim Jong-un's uncle, seems to have been intent on getting rid of his rivals since 2010. His greatest rival Ri Je-gang, a one-time first deputy director of the Workers Party's powerful Organization and Guidance Department, died in a mysterious car accident in May 2010, just a few days before Jang was to be promoted. And early last year, spy chief Ryu Kyong, another apparent rival, was accused of treason following a visit to Seoul and was purged.

Instead, figures considered loyal to Jang now occupy key posts in the regime. New army chief Choe Ryong-hae, Mun Kyong-dok, the head of the party's Pyongyang chapter, Ri Yong-su, the head of the party's labor groups, Ambassador to China Ji Jae-ryong, and Sports Minister Pak Myong-chol -- all have been close to Jang for decades.

Officials who have sided with Jang are generally doing fine. A key example is Kim Jong-il’s last wife Kim Ok, who served as de facto leader when Kim suffered a massive stroke in August 2008. "At that time, Kim Ok deferred to the opinions of Jang and his wife Kim Kyong-hui, Kim Jong-il's sister," an informed source said. "That appears to have guaranteed her status following Kim's death."

But some experts say there are natural limits to Jang's power. "In North Korea, only the Kim family is allowed to reign," said on intelligence source. "Jang's power will last only as long as his wife is alive."

Meanwhile, Kim Jong-un ap pears besotted with a new amusement park in Pyongyang and has conducted four on-site visits so far this year, with pictures from the latest beamed around the world. "Kim has no major accomplishments under his belt and seems to be touting the amusement park to highlight how much attention he is paying to the people," a government official here said.