"Under agreements reached in the Six-Party process, North Korea has committed to declare all its nuclear programs and to disable the three key nuclear facilities at Yongbyon as an initial step toward eventually abandoning all its nuclear weapons and existing nuclear programs," spokeswoman Dana Perino said.

"While it's unfortunate that North Korea has not yet provided a complete and correct declaration, we continue to work with Japan, South Korea, China and Russia in urging North Korea to fulfill its commitments in this regard. We believe the Six-Party framework gives the region and the world the best opportunity to realize the goal of a denuclearized Korean Peninsula," Perino added.

Her remarks followed criticism of Pyongyang by Lefkowitz Thursday in which he argued North Korea is unlikely to abandon its nuclear weapons before US President George W. Bush leaves office in January 2009.

"It is increasingly clear that North Korea will remain in its present nuclear status when the administration leaves office in one year," Lefkowitz told a forum in Washington.

Perino however stressed that: "we have an ambassador (chief US nuclear negotiator Christopher Hill) who is deeply involved in the Six-Party Talks and in his work he is the one most intimately aware of all the developments in those difficult and sensitive negotiations."