GYEONGJU, South Korea — President Bush took a hardline stance against North Korea today, saying the United States won't help the communist nation build a civilian nuclear reactor to produce electricity until it dismantles its nuclear weapons programs.

With the nuclear dispute with North Korea at an apparent impasse, Bush and South Korean President Roh Moo-hyun put the communist regime on notice that it would not be allowed to keep its nuclear weapons programs.

"A nuclear-armed North Korea will not be tolerated," Roh said through a translator.

The North has demanded that it be given a light-water reactor — a type less easily diverted for weapons use — in exchange for disarming. U.S. officials once rejected the idea outright and argued North Korea could not be trusted with any nuclear program, but now have left the door open as long as Pyongyang isn't given a reactor as an incentive but only as a reward after it has eliminated nuclear weapons programs.

"We'll consider the light-water reactor at the appropriate time," Bush said. "The appropriate time is after they have verifiably given up their nuclear weapons and/or programs."

So far, Bush is getting one thing he wanted from his four-country swing through Asia: no public displays of dissension from the United States' partners in the talks.

Negotiations between North Korea and the United States, Japan, South Korea, Russia and China in September concluded with Pyongyang's promising to end its nuclear program in exchange for aid, diplomatic recognition and security guarantees. But a disappointing new round of talks ended last week without progress on the difficult next step — how to dismantle existing weapons and verify that the country has really ended all suspicious programs.

At Bush's meeting with Roh — like that a day earlier in Japan with Prime Minister Junichiro Koizumi — the leaders made clear they remain committed to ending North Korea's program. There was no mention of the differences between the United States and South Korea on how to deal with Pyongyang.

Roh, who has pursued engagement and closer ties with the North, opposes military action if diplomacy fails and is cool to going to the U.N. Security Council for sanctions. Bush has not taken either option off the table.

But, declared Roh: "We have no disagreement at all that this issue must be resolved."

Roh has generally favored a softer approach than Bush toward North Korea, but Roh did not ask Bush to modify the negotiating approach, said Mike Green, senior director for Asian affairs on the National Security Council. "He didn't ask for a more flexible position because" a statement of principles endorsed by all parties in September "was pretty clear," Green said.

South Korea, concerned that it might anger the communist regime in the North and complicate the nuclear talks, said Thursday it would abstain from a vote this week to adopt a U.N. resolution calling for North Korea to improve its human rights record.

The North Korean nuclear issue will continue as a dominant theme during Bush's Asian tour. On Friday, Bush confers with Russian President Vladimir Putin on the sidelines of the annual summit of the Asia-Pacific Economic Cooperation forum. Over the weekend, he travels to China to meet with President Hu Jintao.

Roh's determination to put South Korea on a more equal footing with the United States was on display when the two leaders appeared together. Bush normally dominates such sessions with fellow leaders, even on foreign soil, as he takes most of the questions and does much of the talking.

That wasn't the case this time. Roh spoke twice as much as Bush, who kept his answers brief.

Still, there was none of the language that Roh used during his 2002 campaign that some viewed as anti-American.

Roh repeatedly said U.S.-Korean relations have been strong under his administration. The leaders celebrated the drawdown of U.S. forces in South Korea — already down to 32,500 as almost 5,000 have left in recent years, many for Iraq, and another 8,000 are slated to leave in coming years. Bush also thanked South Korea for sending some of its military forces to Iraq.