The least bad option is stopping the bombings. Japan was at a point when kamikaze attacks didn’t do shit to the navy sitting on their shores. Time had been bought, oil was nonexistent. The horrors of the firebombing of Tokyo dont make the nukes justified. You can cease bombings during negotiations.
And the time before the bomb dropped was the correct time, the Soviets had entered the war against Japan, Japan’s chance at negotiating through a third party was now gone and the walls where closing in. This was the plan. The Soviets stayed out until that point with the intention of the Allies being literally to use that as leverage. The door was left open on purpose
The US drops the first bomb August 6th, August 7th the USSR declares war on Japan (technically telling Japan on the 8th and with the caveat that the USSR would consider itself at war from the 9th on). So yeah I’m gonna go with prior to the Soviets entering the war as per the United States own wishes, as the ideal time for negotiations. The US had broken Japan’s codes and was reading messages like this from Ambassador Sato
“There is no alternative but immediate unconditional surrender if we are to prevent Russia’s participation in the war.”
Yeah we can’t be totally sure until afterwards, but the same is true for letting the peace process actually be attempted as planned. Hindsight works both ways, and given the US admitted it was doing it just to intimidate the Soviets, and the alternative was sitting around for a bit longer and negotiating till that ran dry it is clearwhat the wrong choice was
They had no means to do anything. They had been restricted to the home islands. Also you keep saying “ad hoc” but I think you misunderstand that the navy keeps track of whether or not enemy planes sink their freaking ships. You can kinda keep track of that “hey did that plane blow you the fuck up or did it get shot down” and then get the answer. Pilots keep track of their fucking kills, that is not ad hoc information. The navy tracked the damage done by kamikaze.
They had no fucking navy, Yamato was sent out for a suicide mission and it didn’t even get the chance, it got sunk almost instantly. The military couldn’t do much of anything.