The airlines’ decisions mark the first time in 20 months of tensions in the Middle East that region’s busiest hubs have been hit by cancellations.

More than two dozen U.S. Air Force KC-135R and KC-46A tankers took off from bases across the U.S. and headed east over the Atlantic, The War Zone reported earlier. The U.S. Navy's aircraft carrier USS Nimitz has also appeared to be heading toward the Middle East from Asia.