"This process has had its ups and downs, because any complex negotiating process will," she said during a news conference in Washington. "But we believe that we should keep moving forward."

Rice was responding to reports that North Korea is rebuilding the Yongbyon nuclear facility because the United States hasn't removed it from its state sponsor of terrorism list.

The secretary said the countries involved in the denuclearization of the Korean peninsula continue to work on completing a verification protocol to validate North Korea's list of nuclear activities.

White House press secretary Dana Perino said the Bush administration had seen reports about North Korea reassembling its main facility, but could not confirm that the reports were true.

"Our whole premise has been action for action," Perino said. "We have fulfilled our obligations when the North Koreans have fulfilled theirs."

Once North Korea agrees to a verification protocol, she said, "then the United States would take them off of our state sponsor of terrorism list. But we're not going to do it without it."