President Bush believes it is "troubling, sobering news" that North Korea has a nuclear weapons program, his spokesman said Thursday.

Talking to reporters who accompanied Bush on a trip to the South, spokesman Scott McClellan said the president planned to bring up the issue in talks next week with Chinese President Jiang Zemin.

McClellan said that Bush decided to address the issue through diplomatic channels. "We seek a peaceful solution," he said.

The United States and South Korea, stung by North Korea's admission that it has a secret nuclear weapons program, are calling on Pyongyang to reverse course and abide by promises to renounce development of these armaments.

The startling disclosure, revealed Wednesday night by the White House, changed the political landscape in East Asia, setting back hopes that North Korea was on the road to becoming a more benign presence in the region.

The North Koreans acknowledged the existence of the program during meetings with U.S. officials earlier this month.

Assistant Secretary of State James Kelly called attention to bills of sale and other evidence of commercial transactions as proof that Pyongyang was attempting to produce enriched uranium, an administration official said.

At first, the North Korean officials denied they were pursuing nuclear weapons but then surprised Kelly by admitting that such a program was under way.

The U.S. official, asking not to be identified, said the North Koreans decided to go ahead with the program after President Bush identified the country as a member of an international axis of evil.

Kelly dismissed that suggestion, telling the North Koreans that the U.S. evidence suggested that the program predated Bush's January 2002 remarks, the official said.

Privately, White House officials said Bush and his senior advisers decided to confront the problem in a low-key fashion.

Bush, for example, planned no public statements on it Thursday.

The disclosure adds to the administration's list of foreign policy headaches, coming on top of a possible U.S. attack on Iraq and the overall U.S. war on terrorism.

Said Senate Majority Leader Tom Daschle, D-S.D.: "Two things have to be done immediately. First, they have to open up their country to allow inspections to examine the facilities. And second, they have to agree to destroy whatever weapons of mass destruction they have."