New satellite images have emerged that strengthen analysts' findings North Korea's Soviet-era plutonium-producing reactor at the Yongbyon nuclear site is operating again, according to a Wednesday report by the expert website 38 North.
Surveillance photographs taken from space on Sept. 19 reveal hot waste water flowing out of a drainage tube that is in a new secondary cooling system within the five-megawatt reactor, according to the report.
"This release of hot water indicates that the reactor is in operation and the turbine-powered electrical generators are producing power," reads the analysis written by 38 North image expert Nick Hansen.
38 North -- a project of the Johns Hopkins University -- last month reported plumes of white steam had been spotted being vented near the graphite reactor's steam turbines, a sign that researchers concluded meant the reactor was or close to operating.
In the spring, North Korea declared it would restart the old reactor, which had been disabled under a now-defunct 2007 denuclearization accord, so it could begin producing plutonium for the country's nuclear-weapons program.
An anonymous nuclear specialist with connections to the International Atomic Energy Agency told ITAR-Tass that Pyongyang has the ability to restart the reactor.
"We know that they've been working actively in the area; they have a fairly good potential, they work very fast and they have restored it," the source said, while noting IAEA officials have no way of verifying whether the reactor has been restarted as they no longer have a presence in North Korea.
It could take three to four years for the reactor to actually begin generating plutonium suitable for use in a warhead, according to experts. Once fully operational, the facility could yearly produce just over 13 pounds of plutonium.
U.S. and Japanese defense and foreign-policy chiefs met on Thursday and talked about how to respond to North Korea's nuclear weapons work, among other security matters.
China has been encouraging the two nations as well as South Korea to agree to sit-down for a new round of aid-for-denuclearization negotiations with North Korea. However, Washington, Tokyo and Seoul are demanding assurances first that Pyongyang is willing to give up its nuclear weapons work.
"We are prepared to sign a non-aggression agreement -- providing North Korea decides to denuclearize and to engage in legitimate negotiations to achieve that end," U.S. Secretary of State John Kerry said at a Thursday press conference in Tokyo.
Pyongyang claims its nuclear work is necessary in order to deter attacks from the United States and South Korea. The North in the past has called for a formal peace treaty with the United States as a precondition for shuttering its nuclear program.