The F-35 fifth generation single engine fighter has faced further delays in its entry into frontline service after the Pentagon denied Lockheed Martin permission to begin full scale production of the jet. While the F-35A and B variants entered service in 2015 and 2014 respectively, they are considered far from fully combat ready with several bugs in the design having yet to be fixed among other major issues. The Pentagon’s leading weapons tester Robert Behler noted that the F-35 was still far from fully combat ready, particularly highlighting the fact that all variants of the platform suffered from low reliability and were prone to breakdowns more often than previously anticipated.