Analysis & Opinions - Belfer Center for Science and International Affairs, Harvard Kennedy School

The Real-Life Events of "Oppenheimer"

| July 26, 2023

Christopher Nolan’s film Oppenheimer is outstanding. It’s an immersive biopic, the likes of which will be hard to find elsewhere. The acting, cinematography, and seat-thundering sound, all combine to take audiences into the mind and moral decisions of J. Robert Oppenheimer, the man who led the team of brilliant scientists at Los Alamos, who built the world’s first atomic bomb.

If there were any doubt, this film shows that Nolan is one of the most talented film-makers alive. He is also, I suspect, an historian at heart. Many of his films are about how the past folds into the present. They depict parallel timelines, which come together, or branch apart, skipping forward or reversing. He used that technique superbly in Dunkirk, another historical immersive journey. (His films Tenet and Interstellar dealt with time travel itself). Nolan is also evidently fascinated by the darkest possible sides of mankind. Who can forget that in The Dark Knight, we ultimately discover that the Joker doesn’t even have an end goal with the violence he’s unleashing? It’s violence for violence sake.

Oppenheimer combines many of these themes: good and evil, morality and ethics, death and destruction, and science that changes both history and reality. It’s an epic film, whose subjects live with us today.


It’s easy for an historian to take pot shots at an historical film, pointing out inaccuracies. Doing so is not only unedifying, but it also doesn’t positively advance the conversation.

Oppenheimer is not a documentary. As a director, Nolan of course chooses to emphasize particular themes, and people, in his story, while downplaying others. In my view, there’s nothing wrong with this: if Nolan’s film inspires audiences to read the deeply researched biography of Oppenheimer by Kai Bird and Martin Sherwin, which inspired Nolan to make this movie, or other accounts of the MANHATTAN project, or the Cold War, so much the better. Filmmaking is a creative endeavor. (So too is writing history, as I think most historians would admit if they were honest with themselves).

Oppenheimer gets the big historical moments and subjects right. It depicts Oppenheimer’s inner turmoil, as his research in theoretical physics took him to Cambridge and Europe before the war, to Berkeley, and then in 1942 when he joined the MANHATTAN Project, which became a nationwide $2 billion effort to build an atomic bomb before the Nazis. Oppenheimer’s facility at Los Alamos constituted probably the most talented group of minds ever assembled in a single laboratory. It included twelve eventual Nobel Laureates. Many were eccentrics, with colossal egos and prickly personalities. He managed them well. Oppenheimer’s personal decisions about building the bomb, and the moral ambiguity of killing Japanese civilians to save U.S. soldiers, are vividly played by Cillian Murphy, whose eyes seem to become more piercingly blue, his skin more pallid, and his body more emaciated, as the film progresses.

When Oppenheimer witnessed the first atomic test, called TRINITY, in the New Mexico desert in July 1945, he really did quote from a Hindu sacred text, “Now I am become Death, the destroyer of worlds”. Nolan depicts this scene vividly— in silence, amid white light. And when Oppenheimer met with president Harry Truman, played by Gary Oldman, in the White House after the U.S. dropped two atom bombs on Japan, ending the war, and incinerating tens of thousands of Japanese, the scientist really did say that he had blood on his hands. Truman was wrestling his own demons, as the only man who had—until this point—ever ordered a nuclear weapon to be dropped in war. After their meeting, Truman really did ask “crybaby” Oppenheimer not to be let back to the White House, as the film depicts.

A black and white image of Robert Downey Jr. as Lewis Strauss.

Robert Downey Jr. as Lewis Strauss. Universal Studios

One of the movie’s principal timelines is how, in 1954, Oppenheimer, the “father of the atomic bomb,” had his security clearance revoked. He was accused of being a communist and even a Soviet spy. This was the era of McCarthyism. The architect of Oppenheimer’s downfall, the witch-hunt against him, was Lewis Strauss, the vendetta-driven chairman of the Atomic Energy Commission, played by a barely recognizable Robert Downey Jr. Oppenheimer was later, in the 1960s, rehabilitated. The film’s appropriate bookend, in another timeline, is Strauss’s own downfall, when in 1959 he tried to become Secretary of Commerce, but was blocked by the Senate.


So what’s the truth about Oppenheimer and communism? In the 1930s, and until 1943, Oppenheimer was a Communist sympathizer. The film correctly depicts his personal connections with the Communist Party of the United States (CPUSA)— his brother Frank was a member, his girlfriend Jean Tatlock was a Party member, and his wife Katherine (“Kitty”), played by Emily Blunt, had been a member too,. For Oppy, as his students called him, Marxism was intellectually interesting, but it was also practical. Oppenheimer saw communism as the best defense against the rise of fascism in Europe, which, being of Jewish heritage, was personal for him. Like many others, Oppenheimer sympathized and supported the International Brigades who travelled to Spain to fight with the communists against fascists there. What fellow travelers did not realize at the time: as well as fighting fascism, Stalin was using the war in Spain as a homicidal attack on his ideological enemies, in particular those who followed Leon Trotsky. The NKVD (KGB) ran a crematorium in Spain into which Stalin’s victims disappeared.

By 1943, Oppenheimer’s support for Party causes had shifted, evidently as he realized the enormity of his job at the MANHATTAN Project. By that year, he was assisting U.S. army security in identifying scientists he believed were communists.

Soviet intelligence got close to Oppenheimer. In 1943, as the film describes, an approach was made to him by an academic colleague at Berkeley, Haakon Chevalier. He relayed that a British scientist working in San Francisco, John Ellenton, also depicted in the film, would be able to relay information to the Soviets. Oppenheimer rejected the approach. For reasons that have never been made clear, however, Oppenheimer did not inform the authorities for several months. Over the ensuing years, Oppenheimer gave at least three versions of the story, one involving his brother, Frank, one not. It seems likely that, throughout, Robert was trying to protect his brother from army security.

What the film does not show is the role of a Soviet military intelligence officer, Peter Ivanov, who was tasked with recruiting Oppenheimer. Ivanov’s intermediary was the local Bay Area CPUSA leader, Steve Nelson, with whom Oppenheimer socialized.

Contrary to repeated claims over the years, Oppenheimer was not a Soviet agent. Soviet archives now establish this beyond doubt. He was an enigma, even for the Kremlin. But as the most thorough examination of Soviet espionage in wartime America shows, Moscow’s lack of success with Oppenheimer was not for lack of trying. He was a top target for Soviet intelligence, which assigned him the codenames CHESTER and CHEMIST. He was also being cultivated. But being targeted and cultivated for recruitment is not the same as being a recruited spy. In fact, Soviet intelligence reports about the MANHATTAN Project (ENORMOZ, “enormous”) reveal that, at key points, Stalin’s spy chiefs were frustrated that their operatives had not recruited Oppenheimer. The case about Oppenheimer can now be closed.

A black and white photo of a hearing room packed with people. In the middle is Cillian Murphy as J. Robert Oppenheimer.

Cillian Murphy as J. Robert Oppenheimer. Universal Studios


Soviet espionage inside the MANHATTAN Project constituted the greatest security breach in U.S. history. One of Stalin’s spies deep inside the MANHATTAN project was, as Nolan’s film correctly portrays, Klaus Fuchs, a brilliant theoretical physicist. Fuchs was a German émigré, who fled Nazi Germany to Britain, where he became a British naturalized subject. After the war, the military commander of the MANHATTAN Project, General Leslie Groves (played by Matt Damon), blamed the British for failing to identify Fuchs as a Soviet spy. That’s correct. But as MI5’s declassified dossier on Fuchs reveals, at the time it did not have any positive, reliable, evidence of Fuchs’s communism. MI5 knew he was anti-Nazi, but not that he was pro-Soviet.

Although Oppenheimer doesn’t depict it, Fuchs— whom the Soviets codenamed CHARLES— was not the only Soviet agent inside the MANHATTAN Project: others included a prodigious Harvard scientist, Theodore “Ted” Hall (codenamed MLAD, “Young”), Julius Rosenberg (codenamed ANTENNA, later LIBERAL), David Greenglass (BUMBLEBEE, CALIBER), and another British scientist, Alan Nunn May. Their motivations for betraying atomic secrets was severalfold: they were communist true believers, they thought that atomic weapons were too powerful to be held by one country alone, and they had a (misguided) defense— that the Soviet Union was America’s wartime ally, so they were “only” delivering secrets to an ally. But Nolan correctly shows, when Oppenheimer was approached by Chevalier on exactly these lines, he retorted that it was still treason. Whatever sympathy one has for the logic that one country should not hold a monopoly on nukes, delivering their secrets to one of history’s most murderous dictators, Stalin, is something fundamentally different.

A color photo of President Harry S.Truman standing next to Joseph Stalin at the Potsdam Conference.

President Harry S. Truman, right, standing next to Joseph Stalin, left, at the Potsdam Conference in July 1945.

Soviet espionage inside in the MANHATTAN Project would change history. As Oppenheimer correctly portrays, after the successful TRINITY—seventy eight years ago this month—General Groves sent a message to Truman, who was then in Potsdam, in Berlin’s rubbled outskirts, where he was meeting the British and Stalin. Hitler was dead, Germany defeated, but Japan fought on. At Potsdam, Truman decided to tell Stalin about the new weapon. According to a British note of the meeting, Stalin didn’t seem surprised. As well he should not. Stalin already knew about the atomic bomb— in fact Stalin had known about the atom bomb project for years longer than Truman. Soviet intelligence reported the existence of the Anglo-American bomb project to Stalin in 1942. By contrast, Truman was only informed about the atomic bomb when he became president in April 1945, when president Roosevelt died.

By the time World War II ended, Stalin’s spies had delivered the secrets of the atomic bomb to the Kremlin. Klaus Fuchs and Ted Hall both separately delivered plans for the bomb. Hall delivered his plans to his Soviet contact in nearby Santa Fe, written in milk on a newspaper. A Santa Fe drugstore became a clearinghouse for atomic secrets. Soviet espionage accelerated the subsequent Soviet bomb project, which Stalin threw huge resources at, including dragooning slave labor. When the Soviets detonated their own first atomic weapon in August 1949, it was a replica of the weapon built at Los Alamos and dropped by the Americans on Nagasaki.

Even now, after nearly eight decades, secrets about Soviet espionage in the MANHATTAN Project are still appearing. One Soviet agent only recently to emerge is George Koval (codenamed DEVAL), an American engineer drafted into the MANHATTAN project, where he worked on polonium bomb “initiators” at a facility in Dayton, Ohio. The significance of Koval’s espionage was only revealed after his death in 2006, at the age of 93. Russia’s ministry of defense disclosed that when the Soviets detonated their first bomb, the initiator was prepared to a “recipe” provided by Koval. Russia’s leader, Vladimir Putin, posthumously honored Koval “Hero of Russia,” offering a champagne toast in his honor.


There are some aspects of Oppenheimer that, if it were a documentary, would need to be emphasized differently— and are worth knowing before you see the movie. In the film, the delegation of British scientists arriving at Los Alamos are treated somewhat in passing. It’s worth remembering, however, that the British were working on their own atom bomb project (TUBE ALLOYS) since before the U.S. joined the war in 1941, while Britain fought alone, and the United States remained ingloriously outside the war. When the United States was finally pulled into the war, the British TUBE ALLOYS Project was subsumed into the MANHATTAN Project, with America’s vast more resources. The British brought valuable expertise to Los Alamos— but the team included Klaus Fuchs. I’ll be interested to see in the extras for Oppenheimer whether the British story at Los Alamos got left on the cutting floor.

Nolan correctly describes that one of those who blocked Strauss’s nomination in 1959 was the young Senator from Massachusetts, John F. Kennedy. That’s a nice nod to Kennedy as the great American Liberal icon. But Kennedy’s own previous history with McCarthyism is uglier than this moment depicted. In his earlier political career, JFK failed to stand up to McCarthy— indeed, his brother, Robert, briefly worked for the demagogue. JFK knew that criticizing McCarthy was no way to win votes in his 1953 Senate run; it would open himself up to criticism of being soft on communism at a moment when both sides of the political divide were outdoing themselves to be “tough” on it.

Standing next to an IMAX camera in the desert, Director Christopher Nolan adjusts the hat of Cillian Murphy during filming of Oppenheimer.

Director Christopher Nolan adjusts the hat of Cillian Murphy during filming of Oppenheimer. Universal Studios

My recommendation: go watch this film, watch it again, then read about the history. The issues that Nolan depicts are important to understand because they are not relegated to a distant past. The new world that Oppenheimer created, and the nightmare he feared, still lives with us today. Putin is threatening to use a nuclear weapon in his war in Ukraine, Iran is doing everything it can to procure a nuke, and China is set on increasing its nuclear arsenal. Hostile governments are also, again, targeting Los Alamos. According to a recent report, the Chinese government has illicitly obtained valuable secrets from Los Alamos about hypersonic missiles, which Beijing has used to advance its defense technologies.

Meanwhile, we are on the edge of technological revolutions that will transform our societies this century as much as nukes did in the last: artificial intelligence, quantum computing, and biological engineering. A question at the front of my mind, after watching Oppenheimer: have hostile foreign governments already stolen keys to unlock these new technologies in the same way the Soviets did the atom bomb?

Statements and views expressed in this commentary are solely those of the author and do not imply endorsement by Harvard University, the Harvard Kennedy School, or the Belfer Center for Science and International Affairs.

For more information on this publication: Belfer Communications Office
For Academic Citation:

Walton, Calder."The Real-Life Events of 'Oppenheimer'" Belfer Center for Science and International Affairs, Harvard Kennedy School, July 26, 2023.