There was no need to launch it at all. That's the point. Japan was finished.
By that point we were far more concerned about Stalin's promise - which we now regarded as a threat - made at Yalta to enter the Pacific War 90 days after Germany surrendered. Stalin was punctual about doing so attacking the Japanese in Manchuria on August 8, 1945 exactly 90 days after VE day. Not so coincidentally that was the same day as Nagasaki and a mere two days after Hiroshima.
By that point we were far more concerned about Stalin's promise - which we now regarded as a threat - made at Yalta to enter the Pacific War 90 days after Germany surrendered. Stalin was punctual about doing so attacking the Japanese in Manchuria on August 8, 1945 exactly 90 days after VE day. Not so coincidentally that was the same day as Nagasaki and a mere two days after Hiroshima.
