In November 1977, U.S. Air Force officials expressed mounting concern about the restrictions on their tactical capabilities that resulted from a string of problems with the new F100 engine in F-15 and F-16 fighter jets. The F100 engine, produced by Pratt and Whitney Aircraft, was a powerful new engine that played a critical role in the U.S. air-defense system. Development of the engine had started in the late 1960s, and its performance specifications pushed the envelope of the technological possibilities. Although setbacks had to be expected, there had long been a growing concern about the unreliability of the F100 engine in combat situations. The Air Force felt that Pratt had been largely unresponsive in prior discussions of these problems and was now reviewing its options.