North Korea has secretly built a new uranium enrichment facility, American nuclear scientist Siegfried Hecker told The New York Times on Saturday.
During a visit to the secretive communist nation in November, Siegfried and his Stanford University colleagues were reportedly shown an "ultra-modern control room, operating hundreds and hundreds of centrifuges."
Stephen Bosworth, the U.S. special envoy for North Korea, said Monday that while the revelation was disappointing, it was no surprise.
"This is obviously a disappointing announcement. It is also another in a series of provocative moves" by North Korea, Bosworth said. "That being said, this is not a crisis. We are not surprised
by this. We have been watching and analyzing the (North's) aspirations to produce enriched uranium for some time."
News of the atomic complex follows a report last week that Pyongyang is constructing another light-water reactor.
"I'm on a very quick trip through the region consulting with our partners on next steps in the process of negotiating with the North Koreans," Bosworth said.
North Korea has made these nuclear advances despite being hit with several rounds of sanctions since it first tested a nuclear device in 2006.