The Boeing-made KC-135 is a mid-air refueling aircraft that’s been in service since the late 1950s. The RC-135 was introduced in the 1960s and the WC-135 “Constant Phoenix” in 1965.

An airman marshals an RC-135 Rivet Joint surveillance aircraft into position July 24, 2015, at Al Udeid Air Base, Qatar. The RC-135 Rivet Joint aircraft has maintained a constant presence in the ...