This is an amazing thread, in which Alex Wellerstein, a historian of science, argues that the bombing of Nagasaki was a product of bureaucratic inertia rather than grand strategy. According to Wellerstein Truman was pretty much completely out of the loop in regard to the decision, contrary to his later representations of events. He argues that Truman’s dismay about how events unfolded led him to remove control of nuclear weapons from the military, and also that the bombing had no discernible effect on the Japanese government’s decision-making process in regard to surrendering.
I don’t know any of the relevant literature, so I can’t comment on the soundness of the argument, but . . . wow: