WASHINGTON (Reuters) - The United States targeted a prominent al Qaeda member in Syria with an air strike on Monday and was still assessing the results of the strike, a U.S. Defense Department official told Reuters.

"We will not discuss specific operations or release information about air strikes against high-value targets until we can confirm it was a successful strike," the defense official said, speaking on the condition of anonymity.

(Reporting by Idrees Ali; Editing by Chizu Nomiyama)