A number of unidentified drones have been spotted over three United States Air Force bases in England over the last six days, U.S. officials said on Tuesday. "Small unmanned aerial systems were spotted in the vicinity of and over RAF Lakenheath,

The drones appeared at different times between Wednesday and Saturday and hovered over the Royal Air Force’s Mildenhall, Feltwell and Lakenheath bases

The Air Force didn’t identify who was behind the incursions, but said officials determined there was no impact on residents or critical infrastructure.