BUSAN, South Korea — In a show of unity, President Bush and South Korean President Roh Moo-hyun declared on Thursday that a nuclear-armed North Korea "will not be tolerated" and agreed that the problem should be resolved through peaceful and diplomatic means.

The two leaders spoke at a news conference in Gyeongju, the ancient capital of Korea. About 250 demonstrators, carrying signs that said "Stop Bush," gathered at the train station in the city to protest the president's visit.

Bush and Roh met ahead of a 21-nation trade and economic summit whose members include the leaders of the five countries — the United States, China, South Korea, Russia and Japan — negotiating with North Korea for its nuclear disarmament.

Roh called his fifth meeting with Bush "constructive."

Roh said the second phase of the fifth round of six-party talks should be held as soon as possible in order to find a breakthrough in resolving the conflict. "We have no disagreements at all that this issue must be resolved," Roh said.

"We reiterated that a nuclear-armed North Korea will not be tolerated and reaffirmed that the issue should be resolved through peaceful and diplomatic means," Roh said through a translator.

Bush said the United States would not comply with North Korea's demand that it be provided with a light-water nuclear reactor before it disarms, a stumbling block in the talks.

"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 program."

Roh played down disputes with the United States and said that the current state of relations with the North represented "perhaps the most stable situation between the two Koreas that you have ever seen and the Korea-U.S. dialogue is going on very smoothly."