According to analysis conducted by 38 North, a Washington-based North Korean monitoring project, Kim Jong Un’s regime may have reprocessed more plutonium than Western experts previously thought – meaning the nation may be able to muster a larger nuclear weapon stockpile than once believed.

Satellite images of the radiochemical laboratory at the Yongbyon nuclear plant in North Korea are said to show signs of operational centrifuges that can be used as part of the process to produce the materials needed to fuel a nuclear weapon, as well as signs of short-term activity in the plant’s “Experimental Light Water Reactor,” according to the think tank’s analysis released on Friday.

According to the report, the images 38 North analyzed covered the period of last September through the end of June, and showed “at least two reprocessing cycles” experts were not previously aware of.

“The Radiochemical Laboratory operated intermittently and there have apparently been at least two unreported reprocessing campaigns to produce an undetermined amount of plutonium that can further increase North Korea’s nuclear weapons stockpile,” 38 North posted.