Delegates to the six-party North Korean nuclear disarmament talks have agreed to a three-week recess. Negotiators say fundamental differences are still blocking an agreement that could lead to an end to the dispute.
The Chinese hosts announced the recess Sunday morning, saying the delegations will reconvene in Beijing the week of August 29.
Delegates said the negotiations deadlocked over North Korea's insistence that it be allowed to retain nuclear reactors for non-military use.
The top U.S. envoy to the talks, Christopher Hill, said that issue is non-negotiable.
"The issue came down to North Korea wanting, not only to have a use of nuclear energy, but also to specifically have a right to light water reactors, and light water reactors are simply not on the table," he said.
Light water nuclear reactors can produce weapons-grade nuclear fuel. The United States and at least some of its negotiating partners do not want Pyongyang to have that option.
The delegations are due to return to their respective capitals to consult with their governments and receive instructions.
North Korea entered this latest round of negotiations seeking significant economic aid and security guarantees in exchange for nuclear disarmament.
Mr. Hill says a deal that was presented to North Korea during the previous 12 days of talks - and which Pyongyang has so far rejected - offers much of what the country is asking for.
"This package would virtually solve their energy problems," he said. "It would address many of their economic problems. It would address normalization with the international community, including bilateral normalization. It's a very generous package."
Washington, however, insists that Pyongyang completely abandon nuclear weapons, in a verifiable manner, before these concessions can be given.
Sunday, North Korea's lead negotiator, Kim Kye Gwan, again blamed the impasse on what he called "hostile U.S. policies."
He says North Korea had to produce its own nuclear weapons because of nuclear threats from America.
He also said the United States had to remove its "nuclear threat" from the Korean Peninsula.
Three previous rounds of talks ended inconclusively. North Korea boycotted the talks for 13-months before agreeing last month to enter a fresh round of negotiations. This latest round, although unsuccessful, included the most detailed discussions so far.
The standoff erupted in 2002, after Washington claimed North Korea was running a secret uranium enrichment program.