North Korea appears to have restarted its Yongbyon nuclear reactor, the UN atomic agency has said in a report.
Plutonium, which is used for nuclear weapons, is believed to be produced at the reactor's complex, reports BBC.
The watchdog said the reactor has been discharging cooling water since July, suggesting it is operational.
Yongbyon, a nuclear complex with a 5-megawatt reactor, is at the heart of North Korea's nuclear programme.
This was the first sign of operational activity at the reactor since December 2018, months after US President Donald Trump met Kim Jong-un in Singapore, according to the IAEA.
Yongbyon has long been monitored from afar by experts trying to get an idea of how many weapons the regime is capable of producing.