When the naval Flanker trainer was being conceived the Soviet Air Force was evaluating a replacement for the Su-24 "Fencer" strike aircraft, and it became evident to Soviet planners at the time that a replacement for the Su-24 would need to be capable of surviving engagements with the new American F-15 and F-16. The Sukhoi bureau concentrated on adaptations of the standard "Su-27UB" tandem-seat trainer. However, the Soviet Air Force favoured the crew station (side-by-side seating) approach used in the Su-24 as it worked better for the high workload and potentially long endurance strike roles. Therefore, the conceptual naval side-by-side seated trainer was used as the basis for development of the "Su-27IB" (Russian for "Istrebityel Bombardirovshchik" - "Fighter Bomber") as an Su-24 replacement in 1983. The first production airframe was flown in early 1994 and renamed the "Su-34" (NATO reporting name 'Fullback').