The time schedule on Grove’s project [i.e. the bomb] is progressing so rapidly that it is now essential that statement for release by you [the press release to be issued after the bomb was dropped] be available not later than Wednesday, 1 August.

The President, who was at a conference in Germany, responded in a handwritten note on the back of Stimson’s letter. It is believed to be the only publicly available document in which Truman gives permission to drop the bomb: