The Boeing KC-135R Stratotanker is one of the most important aerial refuelling aircraft in the history of military aviation. Directly derived from the four-engine Boeing 707 airliner, it entered active service in the late 1950s with the specific mission of refuelling the long-range bombers of the U.S. Air Force Strategic Air Command. It is equipped with four underwing turbofan engines, progressively upgraded over time in terms of performance and features, allowing a maximum speed exceeding 930 km/h. It is fitted with a rigid “flying boom” refuelling system located beneath the tail section. It can also be equipped with two additional underwing pods with flexible hose systems. It can carry nearly 100,000 kg of fuel. Over the years, its role has evolved and expanded, increasing the operational range of fighter and attack aircraft, and it has been widely employed in numerous operational missions.