BEIJING — North Korea’s totalitarian regime Tuesday lifted the curtain slightly on plans for a successor to ailing leader Kim Jong Il, with an announcement that his son had been named a four-star general.

However, the decision shortly before the country’s biggest political conference in 30 years raised fears of possible future turmoil in the “”Hermit Kingdom.”” The secretive government didn’t say how or when the younger Kim Jong Un, thought to be 27 or 28 years old, might assume power.

Kim Jong Un’s lack of experience and his junior family position as his father’s third son have caused experts to worry that the transition could be rocky if the elder Kim, who had a stroke in 2008, were to die soon. Even the basic facts about Kim Jong Un remain unknown, including his birth year, his recent activities and what he looks like.

His youth is “”a big problem, but there’s no other choice right now,”” said Jiang Longfan, a professor at the Northeast Asia research institute of China’s Yanbian University, not far from North Korea.

A major power struggle in North Korea would have serious implications for China and South Korea, both of which fear millions of refugees pouring across their borders. For countries beyond the region, there also would be concerns about control of the North’s conventional military and nuclear program capabilities.

Kim Jong Un being the heir apparent while his father is alive is one thing, “”but the question is after his father’s death … that will be the test,”” said Chen Qi, a professor of regional politics at Tsinghua University in Beijing.

To head off potential problems, Kim Jong Il seems to be moving his relatives and key allies into senior government positions to provide a “”support base for Kim Jong Un,”” said Lee Jung-hoon, a professor of international relations at Seoul’s Yonsei University.

Should the elder Kim die sooner rather than later, all bets could be off. “”Who’s to say (the allies) would continue to provide the cushion and the protection,”” Lee said.

Because so little is known about North Korea, though, analysts could only sift through official statements about the ruling Workers’ Party conference on Tuesday, and guess what might come next. “”Outside observations can to some degree be right,”” said Chen, the professor in Beijing. “”Or maybe not.””

The last similar meeting in North Korea, held in 1980, signaled that the mantle of power eventually would be passed from Kim Il Sung to his son, Kim Jong Il. That transition, however, didn’t take place for another 14 years until after Kim Il Sung’s heart attack.

This time, the grooming period could be much shorter due to 68-year-old Kim Jong Il’s reportedly frail condition.

Observers in Seoul and Beijing suspect that Kim Jong Il recognizes the potential hazard, which is why his sister, Kim Kyong Hui, was also named a four-star general on Tuesday. In June, Kim Kyong Hui’s husband had been moved to the important post of vice chair of the powerful National Defense Commission.

There has been some expectation — hedged, as with everything else about the North — that Kim Jong Un might formally be named as next in line for power. For a moment on Tuesday, it appeared that something might be in the works.

On Tuesday afternoon, North Korea’s state TV station said there’d be a “”momentous announcement”” at 2 p.m.

North Korea watchers held their breath — was the conference in Pyongyang about to unveil the crown prince?

When 2 p.m. came, North Korea’s media made it official: Kim Jung Il had been re-nominated as the general secretary of the Workers’ Party.