Source: U.S. National Archives, Record Group 77, Records of the Office of the Chief of Engineers, Manhattan Engineer District, TS Manhattan Project, File '42 to '46, Folder 5B "(Directives, Memos, Etc. to and from C/S, S/W, etc.)."
The written order for the use of the atomic bomb against Japanese cities was drafted by General Groves. President Truman and Secretary of War Stimson approved the order at Potsdam. The order made no mention of targetting military objectives or sparing civilians. The cities themselves were the targets. The order was also open-ended. "Additional bombs" could be dropped "as soon as made ready by the project staff."
25 July 1945
1. The 509 Composite Group, 20th Air Force will deliver its first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets: Hiroshima, Kokura, Niigata and Nagasaki. To carry military and civilian scientific personnel from the War Department to observe and record the effects of the explosion of the bomb, additional aircraft will accompany the airplane carrying the bomb. The observing planes will stay several miles distant from the point of impact of the bomb.
2. Additional bombs will be delivered on the above targets as soon as made ready by the project staff. Further instructions will be issued concerning targets other than those listed above.
3. Discussion of any and all information concerning the use of the weapon against Japan is reserved to the Secretary of War and the President of the United States. No communiques on the subject or releases of information will be issued by Commanders in the field without specific prior authority. Any news stories will be sent to the War Department for specific clearance.
4. The foregoing directive is issued to you by direction and with the approval of the Secretary of War and of the Chief of Staff, USA. It is desired that you personally deliver one copy of this directive to General MacArthur and one copy to Admiral Nimitz for their information.
(Sgd) THOS. T. HANDY
copy for General Groves