The chief U.S. negotiator to talks on North Korea's nuclear program said Wednesday he expected "hard bargaining" over new proposals on Pyongyang's disarmament as envoys began gathering for a new round of negotiations.

The resumption of the six-nation talks, scheduled Thursday, follows a December meeting that ended in stalemate. But since then, signs have emerged of a greater willingness to compromise. Washington improved its offer for disarmament in exchange for security guarantees and energy assistance at a meeting in Berlin that North Korea described as positive.

"The big question is whether the North Koreans are really ready to make some progress," U.S. Assistant Secretary of State Christopher Hill told reporters before leaving Tokyo for Beijing. "We did have some good signs in Berlin, but I think we also know that there is going to be some rather hard bargaining, so we'll see how we do."

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Hill and his counterparts from China, Japan, Russia and South Korea were holding separate two-way meetings Wednesday afternoon. The North Korean envoy was expected to arrive Thursday morning.

Hill said Wednesday evening in Beijing that the Chinese hosts expected the talks to last a few days, and that the sides would start reviewing a draft agreement Friday. No end date has been set for the negotiations.

Kenichiro Sasae, Japan's envoy, said a chief goal is to get Pyongyang to return to a September 2005 agreement — the only accord produced in the more than three years of the talks.

"It's important that we take concrete steps for the denuclearization of North Korea," Sasae told reporters after meeting with his Chinese and Russian counterparts. "Japan is prepared to play its part in the process."

Getting North Korea to relinquish its nuclear program has been a thorny issue for over a decade in Northeast Asia, a volatile corner of the world where suspicions among countries run high and U.S. forces are stationed in South Korea and Japan.

U.S. military action against North Korea could spark a replay of the 1950-53 Korean War when China intervened on the North's behalf against American-led United Nations forces, a Chinese arms control specialist said Wednesday.

"It's one dangerous possibility," Teng Jianqun, a retired People's Liberation Army officer and secretary-general of the government-backed China Arms Control and Disarmament Association, told reporters. "The Chinese government has been trying its best to avoid such a possibility."

Four years ago, North Korea pulled out of a 1994 agreement that froze its nuclear programs after Washington accused Pyongyang of cheating. North Korea has since engaged in negotiations by fits and starts while pursuing a nuclear weapons program which culminated in an October test-explosion of a nuclear device.

In recent weeks, diplomacy among the six countries has ramped up, raising expectations that the current negotiations would result in progress.

Under the 2005 accord, North Korea agreed to give up its nuclear programs while the other countries provided energy and a guarantee that they would not force a change in North Korea's regime.

"The real success will be when we complete the full September '05 statement, not just when we start," Hill said in Beijing. "We're not going to finish that this week. We'll just maybe take a good first step."

The U.S. envoy said Washington was "ready to implement all of the joint statement," including economic and energy aid, but he declined to give specifics.

South Korean nuclear envoy Chun Yung-woo told reports at the Beijing airport that "this is another moment of truth for the six-party talks. This round of talks should create some sort of turning point that shows North Korea's desire to denuclearize."

North Korea walked away from the 2005 agreement after Washington imposed financial sanctions on a small, private bank in Macau, accusing it of abetting North Korean money-laundering and counterfeiting. Though tiny in scope — only $24 million in funds at the Banco Delta Asia were affected — they scared the global financial world from dealing with North Korea.

Pyongyang has insisted that the sanctions be lifted as part of any deal on the nuclear programs. U.S. and North Korean officials met late last month to discuss Washington's allegations and ways for resolving the dispute.

North Korea's nuclear negotiator, Kim Kye Gwan, told visiting Americans last week that Pyongyang also is demanding normal relations with the United States and supplies of electricity or heavy fuel oil, said David Albright, president of the Institute for Science and International Security in Washington.

The North Korean officials were optimistic, Albright said.

"My sense is that they're willing to go for disarmament, but that it's going to be a very slow process, because of the lack of trust of the United States," he said Tuesday.

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