Groves expected to have another atomic bomb ready for use on August 19, with three more in September and a further three in October.
On August 10, he sent a memorandum to Marshall in which he wrote that "the next bomb ... should be ready for delivery on the first suitable weather after 17 or 18 August." On the same day, Marshall endorsed the memo with the comment, "It is not to be released over Japan without express authority from the President."

There was already discussion in the War Department about conserving the bombs then in production for Operation Downfall. "The problem now [August 13] is whether or not, assuming the Japanese do not capitulate, to continue dropping them every time one is made and shipped out there or whether to hold them ... and then pour them all on in a reasonably short time. Not all in one day, but over a short period. And that also takes into consideration the target that we are after. In other words, should we not concentrate on targets that will be of the greatest assistance to an invasion rather than industry, morale, psychology, and the like? Nearer the tactical use rather than other use."

Two more Fat Man assemblies were readied. The third core was scheduled to leave Kirtland Field for Tinian on August 15, and Tibbets was ordered by LeMay to return to Utah to collect it. Robert Bacher was packaging it for shipment in Los Alamos on August 14 when he received word from Groves that the shipment was suspended.