NATO relies on just 14 AWACS (Airborne Warning and Control System) aircraft, which serve as the most important tool for surveillance and air control across its member countries.

NATO’s AWACS planes serve as an early-warning system for the alliance, enabling it to monitor military activities out to a distance of 250 miles.

NATO’s three-week deployment of its E-3 Sentry AWACS (Airborne Warning Control System) aircraft to Norway’s Rygge air base, in the southern part of the country, concluded last week.

Business Insider got access to a NATO AWACS flight on a mission over Eastern Europe. The aircraft, an E-3 Sentry, is decades old and nearing the end of its service life.