George W Bush cautiously welcomes the belated declaration
North Korea has handed over a long-awaited account of its nuclear programme to China.
The declaration, which is six months overdue, is expected to detail North Korea's plutonium production efforts.
But analysts believe it will not go into detail about the country's nuclear arsenal or its alleged uranium enrichment programme.
US President George W Bush cautiously welcomed the move but said the US still had "serious concerns" about Pyongyang.
He said he was notifying Congress of his intent to take the communist state off a US list of state terrorism sponsors in 45 days - if the declaration was complete.
"The United States has no illusions about the regime in Pyongyang," Mr Bush told a White House press conference.
"We remain deeply concerned about North Korea's human rights abuses, uranium enrichment activities, nuclear testing and proliferation, ballistic missile programmes and the threat it continues to pose to South Korea and its neighbours."
North Korea remains one of the most sanctioned regimes
Stephen Hadley US National Security Adviser
The handover is part of six-party efforts offering North Korea diplomatic and economic incentives to disarm.
Mr Bush announced the lifting of sanctions under the Trading with the Enemy Act, but confirmed that other measures against the Pyongyang regime would remain in place.
"It will remain one of the most heavily-sanctioned nations in the world," Mr Bush said.
The US Treasury said sanctions on weapons proliferation, illicit financing activities and money laundering were unaffected by Mr Bush's announcement.
And officials said Washington could re-impose sanctions if Pyongyang failed to live up to its expectations.
The US state department said Pyongyang's declaration would be subjected to an "iterative process of verification" aimed at resolving discrepancies and achieving a "complete and correct" declaration.
This process will include:
Reviewing 19,000 pages of documentation relating to North Korea's nuclear activities dating back to 1986, which was handed over last month
Being given short-notice access to declared or suspect sites related to the North Korean nuclear programme
Being given access to additional required documentation and nuclear materials for sampling
Interviewing personnel in North Korea
South Korean Foreign Minister Yu Myung-hwan said it would be "regrettable" if North Korea's declaration lacked details of Pyongyang's nuclear stockpile.
NORTH KOREA NUCLEAR DEAL
2002: N Korea pulls out of previous deal after US accuses it of having secret uranium programme
October 2006: North Korea carries out its first test of a nuclear weapon
February 2007: N Korea agrees to end nuclear activities in return for aid
July 2007: North Korea closes its Yongbyon nuclear reactor and allows IAEA inspectors in
December 2007: N Korea misses a deadline to hand over a declaration of its nuclear work
June 2008: N Korea hands over nuclear programme details; US cautiously welcomes the move
News of the handover came from the Chinese and South Korean foreign ministries.
In North Korea itself, a senior US diplomat and media have been invited to witness the destruction of a nuclear cooling tower at its Yongbyon reactor on Friday, in an apparent show of commitment to the deal.
Since agreeing to end its nuclear activities in February 2007, North Korea has shut down the reactor.
But reaching agreement with North Korea on the next stage of the disarmament deal - the declaration - has proved a tough task.
Analysts say the most thorny part of the negotiations will focus on what happens to any nuclear bombs and weapons-grade material.
Another expected gap in Thursday's declaration is any disclosure on how the North allegedly helped Syria build what the Americans say was a nearly-completed nuclear reactor.
BBC diplomatic correspondent Jonathan Marcus says the Syrian facility - destroyed by Israeli warplanes in September 2007 - was strikingly similar to the Yongbyon reactor.
He also says that with opinion on Capitol Hill running strongly against Pyongyang, Congress may seek to block any White House move to remove North Korea from its terror blacklist.
Japan, meanwhile, is concerned de-listing North Korea as a terror sponsor could marginalise its efforts to trace Japanese nationals abducted by Pyongyang 20 years ago.
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