North Korea was expected to hand China a long-delayed account of its shadowy nuclear activities on Thursday, a step that may see it removed from Washington's list of terrorist states.
A milestone on the way to ending its nuclear ambitions, the move could also win the reclusive state diplomatic recognition and desperately needed aid and fuel to prop up its economy.
However, U.S. Secretary of State Condoleezza Rice told reporters in the Japanese city of Kyoto that there was still work to do in verifying that North Korea, which tested a nuclear device two years ago, had given up the pursuit of atomic weapons.
"I do think it's important to note that if we can verifiably determine the amount of plutonium that has been made, we then have an upper hand in understanding what may have happened in terms of weaponisation," she said after arriving for a meeting with foreign ministers of the Group of Eight (G8) nations.
"So this (the declaration) is a natural step on the way to dealing with the devices or weapons themselves."
China, the closest Pyongyang has to an ally, has hosted six-country talks that last year secured a deal offering North Korea energy, aid and diplomatic concessions in return for disabling its main nuclear facility and unveiling its past nuclear activities.
That phase of the nuclear disarmament deal was due for completion by the end of 2007, but wrangling over money, aid and the contents of the North's "declaration" has held up progress.
The six-party talks bring together North and South Korea, China, the United States, Japan and Russia.
Officials with knowledge of the latest negotiations said they expected China to receive the declaration late on Thursday.
