It is a well known fact the Nuke bombing of Japan saved probably 1 million or more lives An invasion of Japan would have meant first, bombardment from warships and then the invasion. There would have been untold civilian causalities all over Japan and not just two cities. Now back to the OP please.
That's not a fact. The Japanese were already in talks for surrender and that bomb was just a show of power to Russia.
"I had been in touch with certain Japanese.... They...were ready to surrender provided the Emperor could be saved so as to have unity in Japan. I took that word to Secretary (of State) Stimson at Potsdam July 20, 1945...." - Allen Dulles, CIA Officer.
Something like 3 weeks before Nagasaki & Hiroshima were bombed.
"I personally knew about this as a result of an informal meeting with General Leslie Groves [director of the Manhattan Project]. He said
to me, “You realize, of course, that the whole purpose of this is to subdue the Russians.”
So it was clear that the Cold War had already started during the hot war [World War II]. " - Joseph Rotblat, Manhattan Project scientist.