A pair of prototype aircraft, collectively known as the "VJ 101 C" and individually known as the "X-1" and "X-2", were constructed and participated in a five-year test program. The intention was for the VJ 101 to eventually be developed as the basis for a successor for the German Air Force's inventory of American Lockheed F-104G Starfighter interceptors. However, development of the VJ 101 C was greatly complicated by the changing requirements of the BMVg, who decided to transform the aircraft's envisioned mission profile from the interceptor role to a more general fighter instead, greatly changing the performance requirements for it to fulfil. During 1968, development of the VJ 101 was ultimately cancelled.