How much of an affect was the Soviet declaration of War in the Japanese decision to surrender?

The Soviet declaration of war had the same effect as a coup de grace shot. The shot simply hastened the death. A death that was coming anyway. The importance of the Soviet's declaration of war, was to be legally able to get in on the spoils of war; territorial gain. Which they accomplished. It would also lead to the Korean War, 5 years later. Both the US and the USSR had been gearing up for the cold since 1945. Actually since before that...D-Day! By June '44, the Soviets (Russians) and the Americans were already trying to see who would reach Berlin first. Which is the real reason D-Day was so important. If the Russians (Soviets) took Berlin without US/British involvement, then they might have all of Germany (to themselves).