South Korean President Roh Moo-hyun (search) sought to allay U.S. worries about the North Korean nuclear standoff Tuesday, expressing confidence for a peaceful solution although difficulties remained.

On his first trip to the United States, Roh flew from New York to Washington ahead of a meeting Wednesday with President Bush (search) to discuss North Korea's suspected development of nuclear weapons.

"I do not have any rash expectations that the North Korean nuclear problem can be resolved right away. There will be numerous difficulties ahead," Roh said at a lunch hosted by the U.S. Chamber of Commerce and the U.S.-Korea Business Council.

"But trust will be established among parties, and the door to peaceful resolution will open if the parties involved engage in dialogue with sincerity," said Roh. He described U.S.-South Korean coordination as a "stepping stone" toward a peaceful end to the standoff.

Although the two nations agree that North Korea (search) must not be allowed to develop nuclear weapons, their approaches are different. South Korea wants the United States to be more enthusiastic about talking to North Korea and fears Washington might eventually push for economic sanctions against the isolated North or even resort to military action.

Washington says its demand that the North give up its nuclear programs is not up for negotiation. At talks in Beijing last month, North Korea said it would give up its nuclear and missile programs in exchange for economic aid and security guarantees.

"North Korea is now at a grave crossroad determining whether it will continue in isolation or opt for openness. The choice will not be easy for the incumbent North Korean leadership," Roh said at a dinner hosted by the Woodrow Wilson Center and the Center for Strategic and International Studies in Washington.

Roh described the United States as "our only ally" and said the two countries had an "inseparable partnership." The remarks contrasted with comments during his election campaign last year that were viewed as critical of the United States.

Bush's main objective in Wednesday's meeting is to make face-to-face contact with Roh and project a unified front to avoid any rift that Pyongyang might try to exploit, U.S. officials said. Vice President Dick Cheney also will meet with Roh.

Some White House officials have been pleasantly surprised by Roh's willingness to cooperate. He ran for office promising an equal partnership with Washington but has proved a cooperative partner as the North Korean nuclear standoff has grown more tense.

White House officials expect no breakthrough from the discussion, but they view it as a step in bringing other countries in the region into the issue. Bush meets with Japanese Prime Minister Junichiro Koizumi at his Texas ranch next week, another key step in this process, the official said.

At the meeting in Beijing, the chief North Korean delegate told his U.S. counterpart that his nation had nuclear weapons and was prepared to use them depending on U.S. intentions, U.S. officials said.

Despite that threat, Roh described the Beijing talks as the "meaningful beginning" of a process that could lead to a peaceful resolution.

More meetings have not been scheduled, however, and inter-Korean ties are deteriorating. North Korea said Monday that a 1992 agreement with South Korea not to deploy nuclear arms on the Korean Peninsula was nullified and accused the United States of derailing the deal.

Roh acknowledged that foreign investors in South Korea are wary of the nuclear problem, but he appealed for more business between South Korea and the United States, its biggest trading partner and investor. Bilateral trade amounts to around $56 billion annually.

Roh also pledged to press ahead with market changes to make business practices more transparent and to reduce labor disputes that he acknowledged had been a drawback on the economy.

His schedule Tuesday included a wreath-laying at Arlington National Cemetery, a visit to the Lincoln Memorial and a meeting with Korean War veterans.