The reason the bombs were available to be dropped on Nagasaki and Hiroshima, was because they were not ready in time to drop them on Berlin.
After the two were dropped on Japan, the US had pretty much shot their wad for their nuclear arsenal. There was not enough material to make more for a while, at least several months.
I would suggest a new book, by Robert Wilcox...’Japan’s Secret War’. Very insightful over the Japanese and German nuclear bomb development programs. A lot that the US has said in the past...has not been historical fact, and some of the nuke program for the Japanese was probably fairly close to being ‘done’.
A third one was going to be ready about a week after Nagasaki.
https://outrider.org/nuclear-weapons/articles/third-shot/
“the US had pretty much shot their wad for their nuclear arsenal”
That is what I had thought, but apparently head of the Manhattan Project Major General Leslie R. Grove claimed they would have had a 3rd ready by 8/24, and then they could further produce 3 a month for September and October.
“Groves expected to have another “Fat Man” atomic bomb ready for use on August 19, with three more in September and a further three in October;[87] a second Little Boy bomb (using U-235) would not be available until December 1945.[229][230] On August 10, he sent a memorandum to Marshall in which he wrote that “the next bomb ... should be ready for delivery on the first suitable weather after 17 or 18 August.”
https://en.m.wikipedia.org/wiki/Atomic_bombings_of_Hiroshima_and_Nagasaki
Actually there was a third device in transit when the war ended. But other than that device you are correct.
CC
Actually, that is only partially true. There were no US Bombers, available to drop the extremely heavy and large bombs in the European theater. There was a British bomber that could have if the bombs had been developed sooner.
As it was, the bombing of Japan required two very specially modified Boeing B-29 Superfortress bombers that were modified and tested at the last minute.
We detonated the first atomic bomb on our own soil during WWII as a test.