North Korean leader Kim Jong Il has promoted his son Kim Jong Un to the rank of four-star general.

Experts say the promotion is a sign that the son is slated to succeed his father as leader of the reclusive nation.

The aging Jong Il, 68, is said to be in poor health. Little is known about his youngest son, who has remained out of the spotlight. Jong Un was educated in part in Switzerland and was a big Michael Jordan fan. He reportedly speaks some English.

"We know that he was educated in part in Switzerland. We know that he was a big Michael Jordan fan. We know that he speaks some English. But we can extrapolate from that, having been educated in Switzerland for a couple of years, he knows infinitely more about the West than either his father or his grandfather. And I take that to be a positive indication," said former U.S. Ambassador to Korea Donald Gregg.

"Kim Jong Un's promotion is the starting point for his formal succession to power," said Kim Yong-hyun, a North Korea expert at Seoul's Dongguk University.

"It's clearly the biggest news we've had from North Korea since the death of Kim Il Sung," said Peter Beck, a Council on Foreign Relations-Hitachi research fellow at Keio University in Tokyo.

"I think it clearly demonstrates that Kim Jong Il is committed to maintaining control of the country within his family," he said.

Meanwhile, a ministry to the persecuted North Korean church says it hopes Jong Il's son will make it easier on the communist country's Christians.

Open Doors International says there are an estimated 100,000 Christians in North Korean labor camps where many are tortured and executed.