WASHINGTON -- A U.S. military investigation has concluded that an American airstrike on a March meeting of al Qaeda leaders in Syria was legal and appropriate. But it found several shortfalls in the targeting process that failed to note that damaged and destroyed buildings were associated with an adjacent mosque.

It also concluded there may have been one civilian casualty in the attack in Aleppo that also killed about two dozen al Qaeda members.

Religious buildings are protected. The military must get higher approvals to bomb them if commanders believe they are being used for military or enemy purposes.

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Army Brig. Gen. Paul Bontrager says the destroyed building was a school and a damaged adjacent building was a future mosque under construction.

Syrian opposition activists have said a number of civilians were killed in the strike.

The strikes were carried out by F-15s and drones, CBS Radio News correspondent Cami McCormick reports. The F-15s dropped 10 bombs on the building in the center of the compound, which Bontrager says reconnaissance confirmed was where the meeting was set to take place.