Updated

Stunned by revelations that North Korea has a secret nuclear-weapons program, the United States and South Korea demanded that the reclusive nation give them up.

President Bush called the North Korean admission that it has secretly tried to develop nuclear weapons since the late 1990s "troubling, sobering news," a spokesman said Thursday.

By pursuing nuclear weapons, North Korea has broken a 1994 promise it made to the United States not to develop nuclear weapons. The White House announced the admission Wednesday night.

Fox News was told that North Korea's nuclear program uses highly enriched uranium as the fissile material, as did the U.S. bomb dropped on Hiroshima in 1945.

The news gives the Bush administration another huge foreign policy problem to deal with as it tackles both Al Qaeda's global terrorism and Iraq's possible weapons of mass destruction.

But the White House seems to want to take a soft-spoken course on the North Korean problem.

Spokesman Scott McClellan said Thursday that the president planned to bring up the issue in talks here next week with Chinese President Jiang Zemin.

And McClellan drew a clear distinction between North Korea and Iraq, against which the administration has brought up the possibility of an armed U.S. attack.

"Clearly, North Korea is oppressive, has starved people, but these are different regions, different circumstances," McClellan said. "We seek a peaceful solution."

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.

Congress, South Korea, Japan Demand a Stop to North Korean Nukes

Other politicians were less reticent.

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

Senate Minority Leader Trent Lott, R-Miss., said North Korea has to go on the back burner -- for now.

"Obviously, North Korea is a matter of concern," he said. "But clearly, the one we have to deal with immediately is Iraq."

A senior U.S. official, speaking on condition of anonymity, said North Korea acknowledged having "more powerful" weapons. U.S. officials have interpreted that statement as an acknowledgment that North Korea has other weapons of mass destruction. However, the same officials say they are unsure whether North Korea actually does possess biological or chemical weapons.

Adding to the confusion, U.S. Undersecretary of State John Bolton said there was no question that Pyongyang has weapons.

"In regard to chemical weapons, there is little doubt that North Korea has an active program," he said on Aug. 29.

Bolton is one of the team of officials traveling to the region to discuss the situation with allies.

Presidential spokesman Sean McCormack said North Korea was guilty of a serious infringement of a 1994 agreement with the United States under which Pyongyang promised to be nuclear-free in return for economic assistance.

"The United States and our allies call on North Korea to comply with its commitments under the nonproliferation treaty and to eliminate its nuclear weapons program in a verifiable manner," McCormack said.

"We seek a peaceful resolution of this situation," he said. "Everyone in the region has a stake in this issue and no peaceful nation wants to see a nuclear-armed North Korea."

A senior American official, speaking anonymously, said that North Korea felt it was no longer bound by the 1994 agreement.

"This was not a repentant response," the official said, "not a sign of new openness."

State Department spokesman Richard Boucher said late Wednesday the United States had been ready to offer North Korea economic and other benefits if Pyongyang agreed to curb missile programs, end threats and change its behavior in other ways.

"In light of our concerns about the North's nuclear weapons program, however, we are unable to pursue this approach," Boucher said.

In Seoul, South Korean Deputy Foreign Minister Lee Tae-sik said South Korea has consistently pursued the de-nuclearization of the Korean peninsula in line with international agreements. Japan and South Korea are treaty allies of the United States.

Yim Sung-joon, a national security adviser, said President Kim Dae-jung called the North Korean disclosure a "very serious matter which cannot be accepted under any circumstances."

"We hope North Korea will take a sincere stance toward dispelling suspicions over its nuclear program," Japanese Prime Minister Junichiro Koizumi said.

There was no immediate reaction from North Korea to the White House announcement.

A Troubled Relationship with North Korea

Although President Bush included North Korea along with Iraq and Iran in his "axis of evil" speech this past January, Pyongyang's relations with the U.S., South Korea and Japan have improved markedly since.

Talks with the United States were restarted less than two weeks ago after a hiatus of two years, and it was during those meetings that North Korea dropped its diplomatic bombshell.

North Korea's stunning disclosure about its weapons program came after its remarkable admission just weeks ago that its agents had kidnapped at least 13 Japanese in the late 1970s and early 1980s as part of a program to train communist spies in Japanese language and culture.

The dramatic disclosure complicates President Bush's campaign to disarm Iraq under threat of military force.

It seems unlikely, however, that North Korea will become a target country for the United States as Iraq is nowadays.

With war plans for Iraq already on the drawing board and a broader war on terrorism still under way, threats against North Korea could leave the United States overextended.

Until now, the United States' main concern with North Korea has been its sale of ballistic missiles to Syria, Iran and other countries. Now North Korea's nuclear program has been added to the mix.

The United States has been suspicious about North Korea's nuclear intentions for some time despite the agreement.

A CIA report in January said that during the second half of last year, North Korea "continued its attempts to procure technology worldwide that could have applications in its nuclear program.

"We assess that North Korea has produced enough plutonium for at least one, and possibly two, nuclear weapons."

Assistant Secretary of State James Kelly visited North Korea on Oct. 3-5 and demanded that the communist state address global concerns about its nuclear and other weapons programs.

An administration source said Kelly mentioned evidence that Pyongyang might have a uranium-enrichment program. The program, which the United States believes could only be used to develop a nuclear bomb, began several years ago, according to the official.

Surprisingly, North Korea confirmed the allegation.

North Korea may have foreshadowed the sudden souring of relations 10 days ago when, after Kelly's departure, it called the U.S. diplomat "high-handed and arrogant" and accused him of making "threatening remarks." The United States refused all comment on the discussions.

The Korean peninsula was divided at the end of World War II and remained that way after the seesawing but ultimately inconclusive Korean War five years later. About 37,000 U.S. troops are stationed in South Korea as a deterrent against the North.

The Associated Press contributed to this report.