North Korea has unveiled a secret new uranium enrichment plant equipped with at least 1,000 centrifuges, a US scientist said, raising new fears Sunday about Pyongyang's nuclear ambitions.
Stanford University scientist, Siegfried Hecker, revealed that he toured the facility last week at the Yongbyon nuclear complex, outside the North Korean capital, and said he was astonished by what he found.
"The first look through the windows of the observation deck into the two long high-bay areas was stunning," Hecker wrote in his report posted online.
"Instead of seeing a few small cascades of centrifuges, which I believed to exist in North Korea, we saw a modern, clean centrifuge plant of more than a thousand centrifuges all neatly aligned and plumbed below us."
The top US military officer Sunday said the findings validated Washington's concerns over the isolated Stalinist state's nuclear program.
"From my perspective, it's North Korea continuing on a path which is destabilizing for the region," Admiral Mike Mullen told CNN's "State of the Union" show.
The revelations came as the top US envoy for North Korea was due to arrive late Sunday in Asia for talks with regional leaders on kickstarting the stalled six-party nuclear talks with North Korea.
Stephen Bosworth left for Seoul on Saturday, and was then to travel to Tokyo and Beijing for discussions on the stalled six-party talks on Pyongyang's nuclear program.
Hecker said North Korean scientists told him that construction work on the new facility dubbed the "Uranium Enrichment Workshop" had been begun in April 2009 and was completed just a few days ago.
He was told the new facility included 2,000 centrifuges which were already producing low-grade enriched uranium to help fuel a nuclear power reactor, and added his guides insisted it was for a civilian nuclear electricity program.
The control-room of the facility "was astonishingly modern... and would fit into any modern American processing facility," Hecker wrote in his report.
But he said the North Korean guides insisted that the facility had been built and equipped with local know-how. Pyongyang is currently under UN sanctions in a bid to thwart its nuclear program.
"The 2,000-centrifuge capability significantly exceeds my estimates and that of most other analysts," Hecker wrote, but cautioned: "We were not able to confirm that the facility is fully operational."
The New York Times, which revealed Hecker's findings on Saturday, said the White House had already begun to brief allies and lawmakers about the revelations, which Hecker predicted would spark "a political firestorm."
Administration officials told the New York Times that they had been watching the area where the plant was said to be by satellite, but would not confirm if they knew of its existence previously.
Hecker, who used to direct the Los Alamos National Laboratory, had already revealed when he left North Korea that North Korean leaders claimed to be building an experimental light-water nuclear reactor to be completed by 2012.
North Korea quit the nuclear disarmament talks in April 2009 and staged a second nuclear test a month later. In recent months it has expressed conditional willingness to return to dialogue.
US President Barack Obama warned recently that North Korea must show "seriousness of purpose" before the six-party nuclear talks -- involving the two Koreas, China, Japan, Russia and the United States -- can resume, saying he was not interested in simply "going through the motions."
But some administration officials said Pyongyang might have decided to show off the new facility in a bid to use it as a bargaining chip with the US to try to win something in return for suspending or dismantling the new site.
"They had this capability well in hand and very probably have other facilities," an administration official, who asked to remain anonymous, told the New York Times.
Explore further: Mechanism for aprotic sodium-air batteries