Story highlights The facility served as an ISIS headquarters

The plant was attacked by a dozen aircraft

(CNN) The US has bombarded an ISIS chemical weapons plant that was housed in a converted Iraqi pharmaceutical factory, a top Air Force commander said Tuesday.

Air Force Lt. Gen. Jeffrey Harrigian, the commander of the US Air Force's Central Command, told reporters that 12 aircraft in all were used to hit the facility, which also served as an ISIS headquarters, at 50 different points.

"We don't know for sure at this point" what chemicals were involved, Harrigian said at a Pentagon briefing.

The strike follows a United Nations-backed report issued last month that found that both the regime of Syrian President Bashar al-Assad and ISIS have used chemical weapons in the five-year-long war that has ripped the country apart.

The year-long investigation by the Organization for the Prohibition of Chemical Weapons found in August that Syria's government -- in particular its air force -- had used chlorine gas at least twice since 2013. It also pointed the finger at ISIS for a mustard gas attack

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