Planned tactical nuclear attacks on Japan

While the actual nuclear attacks against Japan in World War Two in the Pacific were strategic bombing of military and civilian targets in Hiroshima and Nagasaki, the evolving U.S. strategy was to reserve additional bombs for tactical use in Operation OLYMPIC, the land invasion of Kyushu.

This initiative came from General of the Army George C. Marshall, Chief of Staff of the Army. He had recommended reassigning the cities still on the list, Niigata and Kokura, to conventional bombin. He expected 8 to 9 bombs would be available for targets on or near the invasion beaches. Each of the three initial invading corps would have three bombs allocated, "one or two, but probably one, as a preliminary, then the landing, than another one further inland against the immmediate suports, and then the third against any troops that might try to come through the mountains from up on the Inland Sea."

The danger of radiation to troops, as well as to construction units building bases from earth contaminated with fallout, was not completely appreciated. It has been speculated that, had the months of delay before the planned November 1945 invasion had taken place, the U.S. might have intercepted enough communications intelligence about Japanese radiation casualties to have reconsidered sending troops through contamination, but this can only be guessed. The plan does support the idea that the U.S. had no specific idea of the radiation effects that were seen at Hiroshima and Nagasaki.