Sung Kim was in North Korea last week and brought back the documents. He said he held substantive talks with representatives from the country's Foreign Ministry and General Department of Atomic Energy and told a State Department briefing Congress would be apprised of what the documents contain as soon as possible.

North Korea had been under a Jan. 1 deadline to outline its nuclear program but missed it. Intelligence data indicate the North Koreans had been sharing their nuclear technology with Syria. Six-party talks involving North and South Korea, China, Japan, the United States and Russia are to resume.

"I do think these documents are an important first step in terms of verifying North Korea's declaration (of its nuclear program). Obviously, the documents themselves alone are not enough. We would need to conduct a very full verification, including access to their facilities, sampling, interviews with personnel involved in the programs. But these offerings are an important first step," Kim said.

Kim said North Korea has yet to discharge spent fuel from its reactor, disable of the control rod mechanism and disable the fresh fuel rods in dismantling its nuclear efforts, although eight other actions have been completed. He said the process has slowed because Pyongyang wants to link it to energy aid.