A US Air Force KC-135R Stratotanker has transmitted the international 7700 general-emergency code while flying near Tel Aviv and Ben Gurion International Airport. Flight-tracking data identified the aircraft as KC-135R registration 62-3500 and showed it operating at roughly 3,900 feet near Ben Gurion when the emergency was reported. Squawk 7700 signals a general aviation emergency and alerts air traffic control that an aircraft requires priority handling. The reason for the alert remains unknown. There has been no indication from US authorities in the material available establishing whether the emergency involved a mechanical problem, a crew issue or another incident aboard the aircraft. The KC-135 is an aerial-refuelling tanker used to extend the range and endurance of military aircraft by transferring fuel in flight. Its emergency near Israel comes amid heightened scrutiny of US military aviation in the region during continuing tensions involving Iran.