Paul Fussell’s essay ought to be required reading for those who quickly dismiss the use of the atomic bomb.
American casualties alone were running at 7,000 a week. Japanese resistance was becoming stiffer as the U.S. approached the home islands. The battle for Okinawa was especially fierce even when the defenders were cut off and that greatly worried American war planners. Civilians were being prepared to wage war to defend the home islands. Projected American casualties for the invasion of Japan were estimated to be as high as one million and Japanese casualties would be much higher.
My own father was one of those American soldiers who had fought the war in Europe and was being readied to be sent to the Pacific. I can assure you that he was not looking forward to it and he was greatly relieved to see Japan surrender.
Japan had no capability to mount an amphibious assault against US military installations or the mainland or even Alaska at the point of Okinawa.
It was all over, but the Japanese war lords would not recommend surrender yet.
There was no urgency to any ground invasion.
Japan could have been blockaded at that point and the rest of its air forces and naval forces destroyed.
The ground forces still on islands could have been starved out by blockade over the years, with selective air attacks as opportunities arose.
It would have been long-term but very inexpensive, especially in terms of American lives.