A US envoy has said Washington will not offer concessions to North Korea before next week's six-nation nuclear talks.
John Bolton has been meeting Chinese officials ahead of talks
Speaking in Beijing, John Bolton said the US would not change its demand that the North must dismantle its weapons programme.
He suggested Pyongyang follow the example of Libya which said it was renouncing its nuclear weapons programme in November.
The talks on the nuclear stand-off are due to start on 25 February.
"I don't think our position has changed from what it's
been for quite some time," Mr Bolton, who is a US undersecretary of state, told reporters in Beijing.
He has been in the Chinese capital meeting officials ahead of the talks.
"The issue really is whether North Korea is prepared to make the commitment for the complete, verifiable and irreversible dismantlement of its programmes," he said.
North Korea has said it will freeze its nuclear programme in exchange for oil shipments and security guarantees from the United States.
Mr Bolton said that there was no difference between China and the US about how to tackle the North Korean nuclear issue.
China is North Korea's last main ally and has played a key role in organising the six-nation nuclear talks, which also include the United States, South Korea, Japan and Russia.
They will be the first talks since the admission by Pakistani scientist Abdul Qadeer Khan that he supplied information on weapons technology to North Korea.
Mr Bolton said that had corroborated the US belief that Pyongyang has not only a plutonium-based nuclear program, but also a uranium-based one.
North Korea has denied the existence of such a programme.
A previous round of six-nation talks ended in Beijing in August without resolution.