Recent commercial satellite imagery provided by the Israeli satellite firm ImageSat International reveals that new construction activity has already begun at North Korea’s Light Water Nuclear Reactor at Yongbyon.

North Korea vowed this week that it was going to restart the reactor, which was shut down and partially destroyed in 2007 as part of international nuclear disarmament talks that have since stalled. But the imagery indicates that the work had already begun between the beginning of February and the end of March, well in advance of Pyongyang’s declaration. The reactor could produce enough plutonium in one year to arm a nuclear bomb.

A crucial step in restarting the reactor will be to restore the disabled secondary cooling system. An unidentified spokesman for North Korea’s General Department of Atomic Energy claimed that scientists will begin immediate work at a uranium enrichment plant and a graphite-moderated 5 megawatt reactor, which generates spent fuel rods laced with plutonium and is the core of the Yongbyon nuclear complex.

While earlier imagery taken in early February shows little to no activity at the reactor site, photos taken at the end of March show construction along the main road leading to the rear zone of the reactor building. There also appears to be some excavation that could be related to replacing some sections of an auxiliary cooling loop that was removed in accordance with the 2007 disarmament agreement.

ImageSat International N.V. is an international company and a commercial provider of high-resolution, satellite Earth imagery collected by its Earth Remote Observation Satellite (EROS). On December 5, 2000, ImageSat successfully launched its first satellite, EROS A, aboard a Russian Start-1 launch vehicle. In so doing, ImageSat became the second company in the world to successfully deploy a nongovernment-owned, high-resolution imaging satellite. On April 25, 2006, ImageSat successfully launched its second satellite, EROS B, using the same type of Start- 1 launcher.