Mr. DiCecco says he and some of the other musicians initially balked at going to Pyongyang and asked about human rights abuses at a briefing in New York by the US envoy, Christopher Hill. Mr. Hill, he says, called the performance "part of getting the ball rolling" toward reconciliation.

People bow in front of a statue of Kim Il-Sung in Pyongyang, North Korea on Feb. 26.       AP/David Guttenfelder

Like Kim Jong-Il, Kim Kye-Gwan and most other top North Korean officials watched the performance on television. Kim Jong-Il never met the visitors.

North Korea's leader might have attended had Secretary of State Condoleezza Rice flown to Pyongyang after Monday's inauguration of South Korean President Lee Myung-Bak. But Ms. Rice went on to Beijing and Tokyo. Kim Jong Il found attending "too difficult" since Rice didn't visit, probably because "the North's declaration of its nuclear programs remains at a stalemate," says Kim Yong Hyun, professor at Dongguk University.

Assistant Secretary of State Hill stayed in Beijing Wednesday, a day after Rice left, to discuss with Chinese officials how to restart the stalled process of dismantling North Korea's nuclear programs.

Under a year-old, six-nation agreement, North Korea agreed to shut down, disable, and dismantle its main nuclear facility and provide a complete accounting of all of its nuclear activities, including its transfer of technology and know-how to other countries. In return, Pyongyang's negotiating partners would provide it with fuel oil, remove sanctions, normalize relations and sign a peace deal.

The Philharmonic musicians left Seoul Thursday night with a sense of having done all they could. "Now it's up to the three [the U.S., North Korea and South Korea] to take it from there," says orchestra chairman Paul Guenther. Adds clarinetist Stephen Freeman, "If it's not followed up, it's a waste of time."