This morning around 10:30 CEST at least one USAF Boeing B-52H left Moron AB, Spain, westbound.
After about two hours the American bomber appeared off Tunisia flying south. During this part of the flight the aircraft has always operated within the Tunisian FIR.
At around 12:30, while the B-52H was flying off southern Tunisia southbound, the aircraft disappeared from the tracking sites probably due to the shutdown of its ADS-B transponder.
At the moment we know if the flight is continuing southwards bringing the American bomber off the coast of Libya but the flight is probably connected to an exercise between US and Tunisian assets that begins today.