I've spent a lot of time thinking about August 10, 1945 (75th anniversary of which is today), because it's where you can really pinpoint the beginnings of Presidential nuclear control in the United States. Thread:

More frequently, scholars invoke Hiroshima for this. That's not quite right; Truman was barely involved in the initial decision to use the bombs, and certainly didn't exercise any control of his office. (At best, he exercised the control of not stopping it.)

And he wasn't involved in the use of the second atomic bomb at all; it's not even clear he knew it was going to occur. It certainly wasn't any kind of decision on his part.

But on August 10th, he did do something big: he stopped further atomic bombings and inserted himself personally into the atomic chain of command.

The context is this: the Japanese had indicated that they would accept the surrender terms of the Potsdam declaration, as much as it "does not comprise any demand which prejudices the prerogatives of his majesty the Emperor." https://history.state.gov/historicaldocuments/frus1945v06/d406

Truman and his cabinet wouldn't accept this — they asked for unconditional surrender, and they wanted it, and this felt like a "condition." (Stimson lamented in his diary that this was exactly the hang-up that he had anticipated and tried to avoid at Potsdam.)

So they were in a dicey situation diplomatically. Truman also, as I said, was probably not aware of the second atomic bombing going ahead until after it had occurred.

In the middle of this, General Groves, head of the Manhattan Project, sends a memo to the Chief of Staff, George Marshall, informing him that they will have the *next* atomic bomb ready for use on August 17 or 18.

This wasn't an "asking for permission" letter. This was sort of a bragging letter — we're ahead of schedule! There's no indication Groves expected a response. But he got one, and quickly — "It is not to be released upon Japan without express authority from the President."

This was conveyed by Marshall, but was Truman's order. Or at least, this is what he told his cabinet that morning: he had "given orders to stop atomic bombing," as recorded in the diary of Henry Wallace.

"He said the thought of wiping out another 100,000 people was too horrible. He didn't like the idea of killing, as he said, 'all those kids.'" It's pretty evocative and specific language — it's hard to imagine Wallace just making it up.

This isn't to say that Truman might not have authorized another atomic strike if Japan hadn't surrendered. He seemed, on August 14th, to be willing to do this, just before Japan gave its notice of unconditional surrender. See my recent article: https://www.nationalgeographic.com/history/magazine/2020/07-08/did-united-states-plan-drop-more-than-two-atomic-bombs-japan/

But if he had ordered another strike — which fortunately he did not have to — it would have been truly *his* order, in a way that Hiroshima and esp. Nagasaki were not. He would be in the driver's seat. The power to use the atomic bomb was his, and his alone.

That's a big shift from how it was handled during World War II, where the President's authority was assumed rather than actually given. And it was considered controversial by the military in the postwar period — why should a civilian be in charge of a military decision?

But Truman very vehemently didn't think nuclear weapons were "military weapons" in the same sense as tanks and bullets. As he said in a meeting in 1948 (recorded in David Lilienthal's diaries), the atomic bomb "is used to wipe out women and children and unarmed people."

The policy of Presidential control of nuclear weapons use was made de facto by the Atomic Energy Act of 1946, but not explicit. It was only made explicit in 1948 (in NSC-30), when it was decided that they'd better hammer this out for certain.

But this was only making formal policy out of an arrangement that had persisted since August 10th, 1945. And Truman, as an aside, guarded that power jealously — he used the Atomic Energy Act to deny nuclear cores to the military for almost all of his Presidency.

Which they protested vigorously! But in the end he only allowed them access to 9 nuclear weapons cores, to be kept on an aircraft carrier near Guam. One can contrast this policy to Eisenhower's to see how deliberate and unusual it was.

The policy of exclusive presidential control over US nuclear weapons use came out of a very different context, where Truman was worried about the dangers of the military running the show. It probably did decrease the chance that they were used in future wars, esp. Korea.

This is still the policy we have today. It's not because it's the only way to run things (not all nations do it this way), but because nobody has changed it since 1945. We can—and should—ask ourselves whether it's still the best policy. https://www.washingtonpost.com/posteverything/wp/2016/12/01/no-one-can-stop-president-trump-from-using-nuclear-weapons-thats-by-design/

But whatever one thinks about it — I think it's a historically significant development, and one that most people date quite wrong. It didn't start with the bombing of Hiroshima; it started the day after Nagasaki. /end