An Atomic Bomb History Expert on the ‘Terrible Moral Dilemma’ in Oppenheimer

The summer’s most popular history-related film is Christopher Nolan’s blockbuster Oppenheimer, about the theoretical physicist and atomic bomb mastermind J. Robert Oppenheimer. The movie comes 78 years after the U.S. dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki on August 6 and 9, respectively, killing an estimated more than 200,000 people. On August 15, 1945, Japanese Emperor Hirohito announced Japan’s surrender, and the document was formally signed on September 2, 1945.

To see how much the movie gets right and wrong about the end of World War II in the Pacific, we called up an expert on this history, former TIME editor Evan Thomas, whose recent book Road to Surrender talks about Oppenheimer and focuses on three key men involved in the decision to drop the bomb: Henry Stimson, the American Secretary of War; Gen. Carl “Tooey” Spaatz, head of strategic bombing in the Pacific; and Shigenori Togo, Japan’s foreign minister.

What Oppenheimer and these characters have in common is that “they all suffered from this terrible moral dilemma of how do you end a war, because you have to kill people to save people,” Thomas says. “And in this case, not just kill a few people, but kill 200,000 people to save more people. Nobody wants to be in that position.”

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In a phone conversation on July 24, Thomas addressed common misconceptions about Japan’s readiness to surrender, whether the U.S. could have won the war in the Pacific without dropping them, and what he thought of the movie.

The following conversation has been lightly edited.

How well did Oppenheimer capture the U.S. decision to drop the bomb?

Here’s the funny thing about the decision to drop the bomb: there was no decision. What do I mean by that? It’s not like a bunch of men sat in a room and they said, “Are we going to drop the bomb or not?” That’s not the way it worked. There was a huge amount of momentum to drop that bomb no matter what. [The U.S.] spent $2 billion on it. In Oppenheimer’s case, he was torn because he worked so hard on it, [and] wanted to know that we could do it. There’s pride involved. There’s ambition. The movie captures that. But it’s not like they’re sitting in a room debating whether to do this. They’re going to do it. There’s a glancing impression that we could have gotten away with not dropping these bombs. That’s not true.

Your book has colorful tidbits about Oppenheimer. You cite Hungarian physicist Leo Szilard’s diary, which claims Oppenheimer said “the atomic bomb is sh-t” at one point— meaning it makes a big bang, but it isn’t useful as a weapon in war.

This shows up in the movie, too. Leo Szilard helped invent the bomb. He wants to stop us from using it. He tried to get to Truman, and he did get to Oppenheimer. Oppenheimer wants to shut him down, so he’s kind of impatient and contemptuous with Szilard, and he said that the bomb is sh-t—just a giant firecracker. It’s a heck of a bomb; it’s not a firecracker, but he’s trying to deflect Szilard.

You talk in your book about how Oppenheimer believed that using the atomic bomb could end all wars because people would see how terrible it was.

Yes, they do capture this in the movie. Oppenheimer knows it’s not really a combat weapon. It’s really a terror weapon. It’s just to terrify people. It’s really not for tactical advantage. The way Oppenheimer chooses to try to control that dissent is by saying, “Look, we use this thing, and we’ll never have to use it again. Because it’s so horrible. This will be the end of the war. People will see how terrible these weapons are, and so they won’t use them again.” Oppenheimer said that in various ways, and that comes through strongly in the movie.

Any myths about this history you want to debunk or set the record straight on?

The big one was that the Japanese were ready to surrender and would have surrendered even if we had not dropped those bombs. I think that is a myth. Oppenheimer seems to have believed that the weapon was used against a country that was about to surrender—as he puts it, essentially defeated. The Japanese were essentially defeated—that’s true. Their fleet had been sunk and their cities had been burned. But they were not ready to surrender.

Did the bombs lead to the Japanese surrender on Sep. 2?

Two atomic bombs forced them to. The dominant reason [the U.S.] used the bomb was to end the war. [The U.S.] thought the only way to end the war was to use these two terrible weapons.

Could the U.S. have won the war without dropping the atomic bombs on Japan?

Yes, they could have by starving the Japanese to death, by blockading Japan and continuing to bomb Japan with conventional weapons. Eventually, Japan would have surrendered. But it would have been a nightmare because there would have been mass starvation. The Japanese were running out of food. The rice crop was not coming in. It is a certainty that there would have been mass famine that fall, that winter. Hundreds of millions of people would have died. There might have been a civil war.

Your book focuses on three men central in the effort to end World War II in the Pacific. Why are they influential?

I chose these three people because they faced intense moral ambiguity. Two Americans were in favor of using the bomb but they struggled with it. Tooey Spatz, who is the Air Force General, writes in his own diary that he’s against using the bomb but he’s convinced that it will save lives. Stimson in his diary worries that science is going to overcome man’s ability to control things— that has some relevance today to AI. Togo is the only senior official in Japan who wants to surrender. It’s not inevitable the Japanese are going to surrender at all. There’s a coup attempt—soldiers running to the palace, trying to break the record of the Emperor’s surrender speech so that he can’t surrender in the morning. It’s that close.

How did the U.S. go from dropping the atomic bombs to calling Japan one of its biggest allies?

The great thing about this country—and it’s not true of every country—is that we are magnanimous in victory. We wanted to create a strong and democratic Japan and working with the Japanese, we succeeded. It was messy. We helped them jumpstart their own economy, and they became our ally pretty quickly against Soviet communism. I’m not saying this was a perfect process. But, by and large, as conquests go, the American conquest of Japan was magnanimous and constructive.

How is studying this period surrounding the decision to drop the atomic bomb in 1945 relevant in 2023?

Nine countries have these weapons. Some of them are not the most stable countries, like Pakistan and North Korea. There’s talk of Russia using [nukes] as a tactical weapon in Ukraine. Wargame scenarios are not all that far fetched. I’ll give you one: the Chinese use missiles to sink American ships. And the United States retaliates by attacking Chinese missile bases on mainland China. The Chinese escalate by using a tactical nuclear weapon against American ships. Now I pray to God that’s never going to happen, but that’s not a totally inconceivable scenario.