Soviets, Stalin knew of its existence well in advance thanks to Fuchs! In lieu of being utterly defeated they refused surrender unconditionally. Ultimately the only condition 'on the quiet' was the Emperor. An Allied landing like Normandy, Operation Downfall , had so few beaches suitable in Japan that everyone, including the Japanese knew precisely where it would be, Allied losses were predicted to b extremely high. The Japanese command was insane, just insane.