The head of Iran’s Atomic Energy Organization announced on Sunday that they will be restarting activity in the Arak heavy water facility to the east of the country.

Iran’s official news agency ISNA ran a story, citing the source as MP Ali Akbar Salehi.

The heavy water plant can be used to manufacture plutonium, which can be used in nuclear weapons.

The announcement by Iran came before the meeting in Vienna, Austria on Iran’s nuclear activities.