North Korea may have restarted its nuclear reactor at Yongbyon, international nuclear watchdog the International Atomic Energy Agency (IAEA) has reported.

In a report released in Vienna on Thursday, the IAEA says it has observed the release of steam and water at Yongbyon, indicating that North Korea has restarted the plant.

The observations were made through the use of satellite imagery and may provide confirmation that North Korea is once again attempting to manufacture weapons grade plutonium.

“Since late August 2013, the Agency has observed… steam discharges and the outflow of cooling water at the 5 MW(e) reactor,” the IAEA said,