The United States has a significant operation underway at Incirlik, including A-10 attack planes, KC-135 refueling tankers and surveillance aircraft, including armed drones. The Air Force has said that American refueling aircraft at Incirlik handled roughly one-third of all refueling operations for the air war over Iraq and Syria.

Use of the base increases the length of time that American and other allied warplanes can remain over Iraq and Syria. The manned and unmanned strike missions from Incirlik, as well as the surveillance missions from there — all located hours closer to the fight than aircraft in the gulf — have made a big difference, according to American officials.

At Diyarbakir, another Turkish base, the Air Force has been staging small numbers of American troops to recover any downed pilots or flight crews.