US Assistant Secretary of State James Kelly on Tuesday said his government was willing to resolve the nuclear issue peacefully, to seek common ground and exercise patience in the second round of the six-nation talks.
China's delegate to the talks, Wang Yi, said North Korea had pledged to be flexible and work hard for concrete results at the talks, which open on Wednesday.
In a separate report it quoted Kim Gye-gwan, the North Korean negotiator, as saying in a meeting with Wang: "The DPRK (North Korea) is willing to show flexibility and work hard to strike concrete results in the new round of six-party talks."
Striking a harder note, a senior Japanese official said North Korea would have to drop its confrontational approach at the talks or it would be difficult to keep the process of negotiations going.
North Korea earlier said the circumstances were better than at the first round in August.
"The circumstances of the talks are better than the previous one, and we hope that we can cooperate closely with China and Russia," North Korean Deputy Foreign Minister Kim Gye-gwan said.
"If the US changed its policy, the nuclear issue could be solved"
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"We appreciate the efforts done by the Chinese side. We will do our best to make a good result at the talks," Kim was quoted as telling the Chinese ambassador in Pyongyang.
But Kim made clear Pyongyang expected something from Washington. "If the US changed its policy, the nuclear issue could be solved."
China and Russia also said on Tuesday they had reached a separate consensus on tackling the crisis.
China wants the talks to produce, at minimum, a written consensus on points of common ground as well as agreement on a smaller working group that would meet more regularly.
Japan's Foreign Minister Yoriko Kawaguchi offered another ray of optimism, telling a parliamentary panel on Tuesday Pyongyang had told China the offer to freeze its weapons programme included the suspected uranium programme.
North Korea recently offered to freeze its nuclear activities in return for diplomatic concessions and aid as a first step towards a resolution of the dispute.
The United States wants the North to commit to the "complete, irreversible and verifiable" scrapping of its atomic programmes.
The talks at the Diaoyutai State Guesthouse in the Chinese capital Beijing, follow six months of shuttle diplomacy after a first round of talks last August failed to narrow the gulf over Pyongyang's atomic arms ambitions.