>>7734259 (lb)
Direct (as the crow flies) route from Mildenhall to Aviano would go through Belgium and/or maybe Holland, Luxemburg airspace into Germany (almost directly over Ramstein AFB) and over Austria into Italy. It would have to skirt the French border at the north end of the Black Forest / Strasbourg, France area a little.
You'd have to think Germany wouldn't be able to stop overflights because of Ramstein, so if there were any overflight bans, as I look at the flight map, it would have to be France and Austria, and maybe Switzerland causing problems. The only country that could cause a huge detour (assuming German overflight) either to the west or east, would be Austria
The way that tanker about kisses the French/Spanish border looks suspicious as hell, though.
Other thing that it could be is that those tankers are refueling aircraft coming from CONUS going to the ME and the tankers are running shuttle between Mildenhall and Aviano. Direct line from Southern CONUS to Avianao or ME would be close to a Spain overflight.
Is there a protocol from refueling over water only? Or, do some countries not allow refueling over their airspace?