Recent satellite imagery shows “suspicious activity” at North Korea’s nuclear complex in what could be a sign that Pyongyang might be trying to harvest weapons-grade plutonium from spent nuclear fuel, a U.S. website monitoring the North said Monday. The website 38 North said in a report that the satellite imagery has shown “exhaust plumes” from a thermal plant used to heat the Yongbyon nuclear complex’s Radiochemical Laboratory, where spent nuclear fuel rods are reprocessed to extract plutonium.

“During the past five weeks, exhaust plumes on two, possibly three, occasions were observed at the Radiochemical Laboratory’s Thermal Plant,” the report said, adding that the activity is “unusual” since exhaust plumes have rarely been seen there and none has been observed on any examined imagery this past winter. “The plumes suggest that the operators of the reprocessing facility are heating their buildings, perhaps indicating that some significant activity is being undertaken, or will be in the near future,” it said. READ MORE