Only a few know that Japan was semi-independently of Germany developing its own A-bomb up until Hiroshima. It developments in Northeastern China and northern Korea. Much of the Soviet initial knowhow of nuclear technologies which produced their first A-bomb in 1949 came from Japanese results they looted at the end of WWII.
It was clear that Japan would not hesitate to drop the A-bombs in Hawaii or San Francisco had it had the bomb and the means to drop it. So all the harpings from the the Japanese far-right (they do exist on the margins of Japanese society) are really revisionist history.
Again, it's not a WWII thread, but:
What was being developed in Korea, Manchuria, Northen China, et. al. by the Japanese was a DIRTY BOMB, not an A-bomb. The vast majority of the research being carried on in those regions was also NBC weapons and techniques, none of which were very successful. P.S., the Germans were in fact seeking the H-Bomb, not the puny A-bomb we settled for, which is why they failed: they made theorhetoical leaps without testing the intermediate steps. This was in addition to having three competing programs (one run by the German Post Office, no less!) which starved each other of funds, mistakes made by scientists, and damage done by Allied air raids (particularly to the heavy water processing plant iin Norway; that's how you know it was an H-bomb -- deuterium and tritium water are used to boost yield by adding extra hydrogen atoms to the reaction).
Japan's government and military had looked into the the research/construction of Atomic weapons and came to the conclusion that they could not afford them. Japanese A-bomb research was never as advanced nor as serious as many people (usually "historians" looking to sell a book or documentary) would have you believe). Trust me; I've read/seen most of them, and I'm an historian (MA Western Civ) myself. They're full of crap.
When the Soviets didn't understand something, the head of their spy program would send a question to Los Alamos and sometimes would receive a reply in 72 hours.
Check out cold war information published by CNN.