North Korea’s Yongbyon nuclear reactor, thought to have been shut down since December 2018, is apparently operating again, according to the U.N. atomic agency. “Since early July, there have been indications, including the discharge of cooling water, consistent with the operations of the reactor,” said a report from the International Atomic Energy Agency. The reactor is allegedly producing plutonium for North Korea’s nuclear weapons program, according to Gary Samore of Brandeis University. “While North Korea already has a significant stockpile of nuclear weapons, this suggests it is moving to expand its current arsenal,” he told The Wall Street Journal. The Biden administration says it has been open for communication with North Korea but that the reclusive nation has not been responsive. “The activities at Yongbyon shows that North Korea’s nuclear weapons program can’t be ignored and needs to be a higher priority for the Biden administration,” a former State Department official, Joel Witt, told the Journal.