October 17, 2014 5:57 PM EDT

Militants from the Islamic State of Iraq and Greater Syria (ISIS) have acquired three “warplanes that can fly and maneuver,” a watchdog Syrian opposition group said in a new report.

The Syrian Observatory for Human Rights said former Iraqi army officials who have joined ISIS are training militants to operate the planes at an airbase near the contested Syrian city of Aleppo. The report, which has not been verified, cites anonymous “reliable” sources. The U.S. military said it’s not aware of ISIS gaining air capability.

“We’re not aware of [ISIS] conducting any flight operations in Syria or elsewhere,” U.S. Central Command spokesman Colonel Patrick Ryder told Reuters.

Write to Justin Worland at justin.worland@time.com.

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