Joseph Stalin's decision to delay the push toward Berlin from February to April 1945 has been a subject of controversy among Soviet generals and military historians, with one side arguing that in February the Soviets had a chance of securing Berlin much faster and with far fewer losses, and the other arguing that the possibility of large German formations (remnants of the Czech fortification system) remaining on the flanks could have resulted in a successful German counterattack and further prolonged the war. Stalin's aim in delaying the advance on Berlin had likely been political, as it allowed him to occupy substantial parts of Austria in the Vienna offensive.