[dfwgator]

Consider this, the Soviets had just declared war on Japan, had we not dropped the bombs, they would have taken their half of Japan, then inevitably there would have been a bloody civil war, just like in Korea with the ChiComs getting involved.

[wendy1946]

Consider this, the Soviets had just declared war on Japan

At Truman's urging and insistence. There was no need. Consider also the 100 American carriers in the region at the time and what Russia would have had available to even try to get to Japan had we not wanted them there (inner tubes, canoes, rafts...)...