A leading U.S. research institute says North Korea has clearly restarted an aging nuclear reactor it had begun to dismantle as part of an international agreement in 2007.
The U.S.-Korea Institute at Johns Hopkins University Wednesday said new commercial satellite imagery provides conclusive evidence that the plutonium reactor at Yongbyon is discharging hot wastewater into a river through a new drain pipe.
Last month, the institute reported signs that the antiquated Yongbyon reactor likely had begun operations, despite Russian warnings that doing so could lead to catastrophe on the Korean peninsula. At that time, Russian diplomatic sources described the reactor as in a "horrific state" of disrepair.
The new disclosure comes as U.S. experts met with North Korean officials to discuss resuming stalled international talks about Pyongyang's nuclear program.
That London meeting came just hours after the United States and South Korea signed an agreement meant to provide greater deterrence against North Korea's nuclear weapons. U.S. Defense Secretary Chuck Hagel and his South Korean counterpart Kim Kwan-jin signed the deal in Seoul during annual security talks.
It was not immediately clear Wednesday how or if the new Yongbyon evidence will impact any future multi-lateral talks.
North Korea last month renewed its call for the resumption of such negotiations on its nuclear program. But the United States -- a key participant in the so-called "six-party talks" -- said Pyongyang first must take "meaningful action" on earlier promises to end its nuclear weapons program.
The North originally shut down the Yongbyon reactor six years ago, under an aid-for-disarmament deal worked out under the six-party format.
But Pyongyang quit the six-party talks in 2009 and has since defied United Nations resolutions with two underground nuclear tests. It also has ignored other UN directives with multiple missile launches and a third nuclear test earlier this year.