US did not expect the aftermath of the atomic bomb. They even had some of their own testing personnel pose near the detonated test bombs site during their experiments. The devastating aftermath that occurred after that is why they have not used their nuclear bombs since. The atomic bombing of Hiroshima and Nagasaki was actually meant to be a show of strength to get Japan to not prolong their war, terror and Japanese occupation in East Asia. Something West or Mid Asians did not suffer from during WW2 and consequently may not understand why most East Asian history books regard the atomic bombings as a necessary means to end the war Japan started in the first place.