Less than a week after a soaring symphony raised hopes of detente on the Korean peninsula, North Korea leveled a new tirade against the U.S. military presence in South Korea, dashing expectations of quick progress in its nuclear standoff. In a further setback, the main US negotiator in the long-running arms talks with Pyongyang headed home Monday having failed to win a meeting with his North Korean counterpart, after lingering in the region following the New York Philharmonic's historic performance in Pyongyang last Tuesday. US officials had warned the good will generated by the emotional concert would be meaningless without North Korea fulfilling its requirements under an international nuclear accord reached last year. The reclusive regime promised in October to lay out its long history of nuclear weapons development in a formal declaration by the end of 2007, a step toward eventually giving up its atomic bombs and the means to make them. In exchange, North Korea was to receive aid and political concessions, including its removal from US terrorism and sanctions blacklists. Washington says North Korea has not yet handed over a full nuclear list, and US Assistant Secretary of State Christopher Hill pressed the country Monday to move quickly on the declaration.