A senior U.S. official says the success of the six-party talks on North Korea's nuclear-weapons program next week depends on Pyongyang's commitment to halting its efforts to build bombs.

Undersecretary of State John Bolton says North Korea's willingness to give up its nuclear capabilities will determine the outcome of the talks opening in Beijing on February 25.

At a news conference in Tokyo, he said that the Bush administration continues to hope for a peaceful resolution to the dispute over North Korea's nuclear programs. Washington demands that the programs be completely and verifiably dismantled.

"The president has been very clear for well over a year that he seeks a multilateral diplomatic solution to the problem of the North Korean nuclear-weapons program," Mr. Bolton said. "He seeks the peaceful elimination of that program. And we have devised a formula that I think is going to be shared by the government of Japan and others in the six-party talks."

Mr. Bolton is in Tokyo to talk over weapons proliferation, North Korea and other security issues with Japanese officials.

He recently said that Washington's commitment to peace could be undermined unless Pyongyang admits all of its nuclear capabilities. In October 2002, U.S. officials said North Korea admitted having a secret program to enrich uranium for nuclear bombs.

Pyongyang denies that, but claims to have reprocessed enough plutonium from spent nuclear rods to make several nuclear weapons in addition to the one or two Washington believes it possesses.

Mr. Bolton, known for talking tough on North Korea, has described the uranium program as an "800-pound gorilla" that cannot be ignored. He was cool to South Korean media reports that Pyongyang may be willing to talk about the uranium program. e said the reports are not a necessarily a sign the stalemate with the North is ending.

He also refused to say whether he was hopeful that the next round of talks would yield concrete results. The first round ended inconclusively last August in Beijing, .

"I think it is not a question of being optimistic or pessimistic. It is a question of being realistic," Mr. Bolton said. "And since the responsibility really lies with North Korea, until we actually hear what they have to say, I do not think we can really prognosticate about the likely outcome."

China, Japan, South Korea and Russia are the other nations involved the talks.