The Sukhoi Su-27 entered Soviet Air Force service in 1985 as a long-range air superiority fighter, designed to counter U.S. fourth-generation fighters like the F-15. It featured high maneuverability, powerful engines, and advanced radar and weapons systems, enabling it to perform both defensive and offensive missions. The Su-27 became the backbone of the Soviet fighter fleet in the late Cold War, securing airspace over the USSR and serving as a platform for subsequent derivatives.