In mid-1943, Adolf Hitler envisioned the Me 262 as a ground-attack/bomber aircraft rather than a defensive interceptor. The configuration of a high-speed, light-payload "Schnellbomber" ("fast bomber") was intended to penetrate enemy airspace during the expected Allied invasion of France. His edict resulted in the development of (and concentration on) the "Sturmvogel" variant. It is debatable to what extent Hitler's interference extended the delay in bringing the "Schwalbe" into operation; it appears engine vibration issues were at least as costly, if not more so. Albert Speer, then Minister of Armaments and War Production, in his memoirs claimed Hitler originally had blocked mass production of the Me 262, before agreeing in early 1944. Hitler rejected arguments the aircraft would be more effective as a fighter against the Allied bombers destroying large parts of Germany, and wanted it as a bomber for revenge attacks. According to Speer, Hitler felt its superior speed compared to other fighters of the era meant it could not be attacked, and so preferred it for high altitude straight flying.