A U-S think tank has released satellite photos showing that North Korea may have closed a nuclear reactor early this month.

The Institute for Science and International Security in Washington on Monday said the photos shows steam plume coming from the Yongbyon reactor's cooling tower on January 7th, but none on April 7th.

ISIS President David Albright, a former inspector at the International Atomic Energy Agency, said the unloading of spent fuel rods for reprocessing and plutonium extraction to make nuclear weapons might follow the shutdown.

Meanwhile, the New York Times on Sunday reported that commercial satellite photos show that the plant was apparently shut down or had its power level greatly reduced at least ten days ago.