UNITED NATIONS (AP) — The Islamic State extremist group has taken control of a vast former chemical weapons facility northwest of Baghdad, where remnants of 2,500 degraded chemical rockets filled decades ago with the deadly nerve agent sarin are stored along with other chemical warfare agents, Iraq said in a letter circulated Tuesday at the United Nations.

The U.S. government played down the threat from the takeover, saying there are no intact chemical weapons and it would be very difficult, if not impossible, to use the material for military purposes.