Japan was working on the Atom bomb as well and was very close, if not already successful in 1945. What would a delay of six more months have brought? Could you imagine first Pearl Harbor being nuked, then San Francisco, Seatle, and LA? Japan had already developed a sub that carried a plane. They had no shortage of suicide pilots and submariners either. If they couldn’t fly a bomb in, they could submarine one in. Japan was working on a lot of nasty stuff besides the Atom bomb too. I say it was close.
“Japan was working on the Atom bomb as well and was very close, if not already successful in 1945”
That’s not true at all.
The Japanese nuclear research project was FAR FAR FAR behind the Manhattan Project.
The Japanese didn’t have the knowlage, resources, facilities or technology to produce weapons grade HEU or a working bomb.