Delegates from six nations have arrived in China ahead of unprecedented talks on North Korea's nuclear ambitions. Six countries will be represented at the Beijing talks - North and South Korea, Russia and China, Japan and the United States. Starting on Wednesday they will be discussing how to end the 10-month row over North Korea's insistence on resuming its nuclear programme. Optimism about the success of the summit, which comes after months of delicate negotiation, is not high. Russian Deputy Foreign Minister, Alexander Losyukov, said he would work to ensure everyone stayed at the table at the talks but that the chances of a deal were very poor. **Fair exchange*** Former US ambassador to South Korea, Stephen Bosworth, agreed with the gloomy assessment and said the level of mistrust was very high. "We have to recognise we're at the beginning of what under the best of circumstances will be a very long difficult process," he told the BBC. I think this meeting will be judged a success if the participants can agree on the need to have a second meeting." But US assistant secretary of state, James Kelly, was more optimistic. "We'll be getting going on Wednesday morning and we're looking forward to a direct and fair exchange of views," he said. The North Korean negotiator, deputy foreign minister Kim Yong Il, was the last to arrive in China. He smiled and waved at waiting reporters, but did not comment. The BBC's Louisa Lim, in Beijing, says just how much the talks can achieve remains to be seen. Pyongyang says it will not relinquish its nuclear weapons programme unless there is a change to what it sees as a hostile US policy towards it. But the US is determined not to reward what it sees as bad behaviour. The crisis, which has soured already tense relations, started in October when the US announced that North Korea had admitted to a secret nuclear arms programme. Since then North Korea has restarted a mothballed nuclear power station, thrown out inspectors from the UN's International Atomic Energy Agency and pulled out of the nuclear non-proliferation treaty. **Border clash*** The US wants Pyongyang dismantle its nuclear weapons programme in return for some kind of security guarantee that the US would not attack. China's Xinhua news agency quoted China's Vice President, Zeng Qinghong, as saying that North Korea's security concerns should be addressed. He said China had always stood firm on the principle of maintaining peace and stability on the Korean peninsula and would "actively encourage the parties to solve the nuclear issue through peaceful dialogue". The day before the talks are due to start South Korea said its navy fired warning shots after a North Korean patrol boat crossed a disputed border off the west coast of the divided peninsula. A spokesman for the joint chiefs of staff said the North Korean vessel then returned to the North. **PHOTO CAPTION*** A North Korean man stands next to a portrait of former North Korean leader Kim Il-Sung during a visit by South Korean businessmen to the border town of Kaesong, August 25, 2003. (Pool via Reuters)