In Beijing, negotiators are trying to cobble together an action plan detailing steps North Korea should take to disable its nuclear facilities.
U.S. Assistant Secretary of State Christopher Hill told reporters Friday there are still differences to be resolved on how North Korea's nuclear capabilities might be disabled.
"Frankly, we'd like more and they'd like less. And we'll see what we end up with," he said. "But we don't have an agreement on what constitutes disabling yet."
Hill, with his counterparts from North Korea and South Korea, China, Japan and Russia, resumed discussions Friday, hoping to draw up a step-by-step action plan for the denuclearization process.
The talks are aimed at persuading North Korea to disable its nuclear facilities in a verifiable, complete and irreversible manner.
Hill earlier said the North has already accepted certain proposals, but no details have been released.
The five other nations want North Korea to stick to its promise to disable its nuclear facilities and declare all its nuclear activities by the end of this year. The other side of that agreement, reached last February, is that North Korea will receive economic aid, fuel and security incentives. Many details are yet to be resolved before the deal can become final, however.
In 1994, North Korea signed a similar agreement to shut down its nuclear facilities, but later restarted them. Hill, emphasizing that any shutdown this time must be complete and irreversible, has said the U.S. will not take a "trust me" from Pyongyang any longer.
The four-year-long diplomatic effort, which has stalled at times, gained urgency after North Korea conducted its first nuclear explosion in October last year. The negotiators say this week's round, due to end Sunday, is a critical step in the process.