The Boeing 707 was the most successful and versatile of the early jet airliners. This versatility led to a wide variety of subsequent military roles. The USAF first used the type as the basis for an Airborne Warning and Control (AWACS) platform designated E-3 Sentry.

The E-3 Sentry is a modified Boeing 707/320 commercial airframe with a distinctive rotating radar dome. The dome is 30 feet (9.1 meters) in diameter, six feet (1.8 meters) thick, and is held 11 feet (3.3 meters) above the fuselage by two struts. It contains a radar subsystem that permits all-weather surveillance over a range of more than 200 miles (320 kilometers) for low-flying targets and farther for aerospace vehicles flying at medium to high altitudes. The radar combined with an identification friend or foe (IFF) subsystem can look down to detect, identify and track enemy and friendly low-flying aircraft by eliminating ground clutter returns that confuse other radar systems. Canadian crews are integrated into USAF E-3 Sentry operations within North America as part of Canada's contribution to NORAD. NATO subsequently acquired a fleet of eighteen Sentry aircraft to provide airborne surveillance, command, control and communication for NATO air operations. Home based in Geilenkirchen, Germany, NATO aircraft are routinely forward deployed and Canadian military personnel serving with NATO also make up part of the associated air and ground crews.