Due to export restrictions by the Department of Defence preventing sales of advanced avionics and aircraft to export customers, many allies who were flying the now out-dated F-5 could not purchase the latest F-16 aircraft to meet the threat of the latest MiG-29s and Su-27s that Soviet allies were receiving. As a result, Northrop Grumman initiated the FX program, to design and build a new 4th light export generation fighter on the basis of the cancelled F-5F Super Tiger. The primary requirements for this new fighter were cheap interoperability with existing F-5 fleets, BVR capability, and modular compatibility with almost every kind of ordnance the US offered for export at the time.