An unofficial delegation of Americans flew to North Korea (search) on Tuesday as part of what one called a visit to increase understanding -- and perhaps offset the persisting standoff between the two nations over Pyongyang's nuclear program.

The visit began on the same day that the North offered to refrain from testing and producing nuclear weapons as "one more bold concession" in trying to rekindle six-nation talks on the standoff. It also said it was willing to halt its nuclear activities for peaceful purposes.

The American group, including a former government official and a retired academic, passed through Beijing (search) on Tuesday morning en route to the North Korean capital for its five-day stay.

"It's a very private visit. We're not representing the U.S. government or anyone else," said Jack Pritchard (search), once a member of former President Bush's National Security Council staff and a one-time State Department official.

"We're going in as private citizens. We'll come out Saturday and you can mob us then," Pritchard told reporters at Beijing's Capital Airport.

The North Korean nuclear crisis flared in October 2002 when U.S. officials accused North Korea of running a secret nuclear weapons program in violation of a 1994 deal in which North Korea is obliged to freeze its nuclear facilities. Washington and its allies cut off free oil shipments, also part of the 1994 accord.

Members of the group refused comment on reports that they might visit a nuclear complex in the North.

"Our expectation is we'll improve understanding. We'll clarify some issues," said John W. Lewis, professor emeritus of international relations at Stanford University. "I'm a professor, and that's what we do. We try to make things clearer. We'll try to make people understand each other better."

He added: "There's economic issues, political issues. We have scientists with us, so we'll have a whole series of things. ... It's not just a weapons grade thing."

Also on the trip is Sig Hecker, a nuclear specialist at the Los Alamos National Laboratory in New Mexico.

A pair of U.S. congressional staffers are scheduled to visit Pyongyang this week.

Chinese and Russian officials met in Moscow on Monday to try smoothing a way toward a new session of six-nation talks. A first round of talks in Beijing in August ended with little progress.