North Korea has given the United States key documents related to its past nuclear activities and the operation of its main nuclear reactor in Yongbyon.

State Department spokesman Sean McCormack told reporters Thursday that the department's point man on Korean affairs, Sung Kim, will return home soon with a significant number of documents related to North Korea's plutonium program. Earlier in the day, Kim held extensive talks in Pyongyang with North Korean officials on their country's nuclear declaration.

McCormack said the U.S. will be able to assess the documents' significance in the weeks ahead. He said in doing so, it will consult closely with other members of the six-party nuclear talks.

The papers, amounting to thousands of pages, are expected to become the key to verifying an eventual declaration from Pyongyang on its nuclear programs and materials.

Foreign media, including The Associated Press, said the development meant a step forward for Washington in obtaining a full account of the reclusive state's nuclear past. The AP said the documents could also build confidence among conservative critics of the recent, relatively flexible U.S. posture toward Pyongyang.

The Wall Street Journal, meanwhile, said U.S. President George W. Bush is likely to ask Congress to remove the North from the State Department's terrorism blacklist after reviewing the paperwork.