The U.S. Air Force is using a significant number of Boeing [BA] KC-135 and KC-10 tankers and C-17 Globemasters to enable the evacuation of U.S. and allied personnel and Afghan civilians from Kabul International Airport, per flight tracking and open source intelligence analysts who monitor flights through the FlightRadar24 app.

The U.S. shut down air operations at the airport on Aug. 16, as 2,500 U.S. troops secured operations there, but DoD said by press time on Aug. 16 that air operations have resumed. Before the temporary closure, Afghans anxious to flee the Taliban had crowded landing strips, and at one point packed inside a C-17, which took off with more than 800 passengers. The Taliban took over the presidential palace in Kabul on Aug. 15.

The compiled flight tracking data reveals that the U.S. has used at least 35 KC-135s, 12 KC-10s and 44 C-17s to form an “air bridge” for the evacuation from Kabul.

The use of 35 KC-135s is more than half the number–60–deployed for Operation Enduring Freedom in 2001. Operation Iraqi Freedom in 2003 saw the use of 149 KC-135s and 33 KC-10s, while Operation Desert Storm in 1991 saw the use of 260 U.S. KC-135s and KC-10s.

Tankers are vital, as countries surrounding Afghanistan have denied the use of their airbases for the airlift.

One defense analyst, Robert Hopkins, a retired RC-135 Cobra Ball pilot and author of The Boeing KC-135 Stratotanker: More Than a Tanker, suggested in a Tweet that the significant demand for tankers to cover the Afghan airlift raises the question of whether the Air Force’s planned buy of 179 Boeing KC-46A Pegasus tankers will be enough, as those 179 are to replace 440 KC-135s and KC-10s.

Other aircraft involved in the Afghan airlift and protection for the evacuation include Lockheed Martin [LMT] C-5s, C-130Js, KC-130Js, MC-130Js, AC-130W and AC-130J gunships, Boeing RC-135W Rivet Joint and B-52 bomber aircraft, and an E-11A Battlefield Airborne Communications Node (BACN) aircraft by Bombardier and Northrop Grumman [NOC].

President Biden said on Aug. 16 that while he decided that nation building in Afghanistan is futile after nearly two decades of U.S. military presence there, U.S. forces are poised for “over the horizon” counterterrorism strikes, should the Taliban pursue terrorism against the U.S.