SHENYANG, China (AFP) - Six-nation talks on North Korea's nuclear programme entered a second day here Friday, marking what the US envoy called a "tough" new phase in efforts to get the reclusive state to disarm.
The working-level meetings brought senior envoys and expert teams to the city of Shenyang in China's northeast, close to the border with North Korea.
"This is a tough phase, because this is the phase that takes us beyond where we've been before, beyond the shutting down of facilities," chief US negotiator Christopher Hill told reporters late Thursday.
The talks, due to end later Friday, are centred mostly on what North Korea, which conducted its first atomic test last year, needs to do to honour a disarmament deal reached in February after tortuous negotiations among the six.
After a first day of meetings in Shenyang, Hill suggested all participants may not be speaking the same language when they talked about disabling the nuclear programmes.
"We have to come up with common definitions, so that we're satisfied that when they say they are disabling, we know what they're doing and we agree that it is disablement," he said.
"(But) disablement is not just putting a reactor out of commission for three days. Disablement has to be something more than that."
North Korea honoured its initial commitments last month by closing its main nuclear reactor at Yongbyon and opening its doors to UN International Atomic Energy Agency inspectors.
But the so-called "declare-and-disable" phase, the second step in the February accord, threatens to be much tougher to conclude successfully.
The United States has insisted the communist nation must come clean on all its nuclear weapons programmes -- providing a "declaration" of all its activities -- for the process to move forward.
"Clearly the declaration needs to involve all nuclear programmes, all nuclear materials, so obviously we need to ensure we have clarity on that," Hill said late Thursday.
The United States suspects North Korea is running a secretive highly enriched uranium programme in addition to the projects it has already admitted to, which were mainly centred on the plutonium-producing reactor at Yongbyon.
Both highly enriched uranium and plutonium can be used to make nuclear weapons.
On Thursday, North Korean delegates voiced willingness to "resolve" this issue, Hill said, but added he did not see any real difference from what they had said previously.
"How you define 'resolve' could take some time," Hill said after Thursday's meeting.
North Korea has never admitted to having a highly enriched uranium programme.
As part of the six-nation accord, North Korea will receive fuel aid, security guarantees and diplomatic concessions. It has already received 50,000 tons of fuel oil for closing Yongbyon.
While highly technical, the talks in Shenyang are considered vital to enabling further progress in the next round of full six-nation disarmament meetings in Beijing, tentatively set for early September.