The expected transfer of power to Kim's youngest son could have unpredictable consequences in the isolated nation, South Korean Defense Minister Kim Tae-young said during a visit to the Pentagon.
"When Kim Jong Il's health may deteriorate, or if there's a movement of public opinion in North Korea, we cannot eliminate the possibility of there being an instability situation in North Korea" that would affect the security of the whole peninsula, Kim said through an interpreter.
He did not elaborate, but some experts warn that the North could try to raise the prestige of its next leader by launching missiles or attacking South Korean targets. Others have said change at the top could trigger a military coup or a popular revolt.
North Korea has maintained a tight grip on its people and economy over six decades, while it pursued nuclear and missile technology and repeatedly defied international demands to disarm.
U.S. Defense Secretary Robert Gates, who spoke with his South Korean counterpart, told reporters it is not clear that the North's current leader's son, Kim Jong Un, would steer his country differently than his father. In a joint statement following two days of talks, both the U.S. and South Korea said that they "will not accept North Korea as a nuclear weapons state."
There are signs of improving relations between the Koreas, including plans for reunions of families divided by the Korean War and talk of reviving a joint tourism venture.
But the U.S. also has deep concerns. North Korea quit U.S.-backed disarmament talks two years ago, stands accused of torpedoing a South Korean warship, the Cheonan, in March and may be seeking to resurrect its partially dismantled nuclear weapons program.
Some experts say North Korea may be trying to create the illusion of a thaw while it presses ahead with its nuclear program and reorders its political leadership.
"There's a lot of speculation about the circumstances that lay behind the sinking of the Cheonan and whether other provocations may follow," Gates said. "Provocations will not be tolerated."
The South Korean defense minister said North Korea must take responsibility for the sinking and apologize before relations can improve.
He said there are no indications that North Korea plans to disrupt an upcoming meeting of the Group of 20 economic powers in South Korea. "But we will go about watching against North Korean threats and any possible North Korean provocations," he added, including stepped up surveillance in concert with the United States.
Also Friday, nuclear proliferation experts said North Korea may be moving ahead with a program to enrich uranium to make nuclear weapons.
Pyongyang has moved beyond laboratory-scale work and is now capable of building a "at the very least, a pilot-scale" plant of centrifuges to enrich uranium, said a report by the Institute for Science and International Security.
The same Washington-based group also recently reported that satellite images show new construction in the area around North Korea's nuclear reactor at Yongbyon, where it once produced plutonium for nuclear weapons.
The work is reportedly continuing at the same time that North Korea's leadership seems to have chosen a successor to Kim Jong Il.
A top official told broadcaster APTN on Friday that North Koreans will be honored to follow Kim's son as the third-generation leader of the reclusive communist nation.
The official's words underscored recent political moves in North Korea that seemed to seal the younger Kim's role as leader-in-waiting.
At the State Department, spokesman Mark Toner said that no matter who is in charge in Pyongyang, the U.S. will demand that North Korea abandon its nuclear weapons. "We view that as an internal political matter and it really doesn't change our position," he said.
Paul Stares, an expert on Northeast Asian security at the Council on Foreign Relations, said it would be "irresponsible" not to prepare for numerous possible changes in North Korean behavior as leadership passes to a new generation.
"But there could also be provocative behavior," Stares said. "There could be possible unwelcome situations if there is a desire to burnish the credentials of the heir apparent by generating external provocations like the Cheonan or something else."
Victor Cha, who advised former President George W. Bush on North Korea, said that a leadership change would not reduce Pyongyang's reliance on ally China or loosen its grip on its centralized economy.
"Major economic reform for a political system like this is extremely risky," said Cha, now at the Center for Strategic and International Studies.
"It is about the most risky thing that a closed regime can do and it is exponentially more risky if it is a closed regime going through a transition."
Source: cbs4denver & © 2010 The Associated Press