North Korea's young leader, Kim Jong-un, is apparently demonstrating swift ruthlessness in eliminating his potential political rivals with reports that his uncle Jang Song-thaek has been ousted from all of his key posts, a U.S. expert said Tuesday.

Alexandre Mansourov, who has long studied North Korean issues, said Kim seems to be following in his late father's footsteps. His father, Kim Jong-il, purged his own uncle Kim Yong-ju, regarding him as a threat to his power bid in the mid-1970s, said Mansourov.

"If true, Jang's removal from power will be a major development in North Korea's post-Kim Jong-il history," he told Yonhap News Agency.

Mansourov issued a report a year ago raising the possibility that Kim Jong-un was going to "use Jang for as long as he had to, but then he would surely cut him off, probably without much regret."

Jang's dismissal, if confirmed, would add to evidence that Kim, who took over power in December 2011, continues to purge the guardians appointed by his father in order to consolidate his power, said Mansourov.

Ri Yong-ho, who was deemed as another regent for Kim, reportedly aged around 30, was ousted in July 2012 from the influential post of chief of general staff vice marshal.

But Mansourov, a visiting scholar at the U.S.-Korea Institute at the Johns Hopkins School of Advanced International Studies, said it's still early to conclude that Jang has been purged.

"At this point, I am waiting for the final confirmation of his downfall," he said. That would come in the form of a report to South Korea's lawmakers by the state spy agency, he said.

North Korea has not made an announcement on any re-shuffle involving key officials.

An important indication will be whether Jang fails to show up in his customary place next to the North Korean ruler in the leadership lineup at the Kumsusan Palace of the Sun for a major annual ceremony on Dec. 31, he said.

The U.S. government, meanwhile, would not comment on the reports of Jang's dismissal.

"I've seen those reports and just don't have anything for you on that. Obviously, I refer you to them to address those issues," Marie Harf, the State Department's deputy spokeswoman, said at a press briefing. (Yonhap News)