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Espionage in Oppenheimer: The Fuchs Spy Mission Explained

A minor mention in Christopher Nolan's Oppenheimer movie was actually a big-deal spy story.

By Tara Bennett

A central conflict that runs throughout Christopher Nolan's Oppenheimer (now streaming exclusively on Peacock) is J. Robert Oppenheimer's (Cillian Murphy) curiosity and measured sympathies with certain tenets of communism vs. the United States' distrust and concern that those sensibilities would lead to his betrayal of the country. In fact, Nolan structured the film visually to reflect the scientist's world view in color and Atomic Energy Commission chairman Lewis Strauss' (Robert Downey Jr.) in black-and-white. 

While the two men were metaphorically and ideologically duking it out in backroom office investigations and public Congressional hearings, the real threat everyone was worried about was happening under their very noises in Los Alamos. One of the Manhattan Project scientists, Klaus Emil Julius Fuchs (Christopher Denham), was a German theoretical physicist actively spying and relaying data for Russia.

In the scene above, Strauss convenes Oppenheimer, Vannevar Bush (Matthew Modine), Ernest Lawrence (Josh Hartnett) and other key Manhattan Project scientists together after the bombings of Japan to discuss intel that points to likely nuclear bomb testing in Russia. It's Strauss' "proof" that the Los Alamos National Laboratory wasn't as secure as General Leslie Groves (Matt Damon) or Oppenheimer had hoped.

In the third act of the Oppenheimer, it comes out that Fuchs was identified as the scientist feeding Project Manhattan data to outside countries. However, he was not personally vetted by Oppenheimer which meant he was never held responsible, or knowledgeable, about Fuchs' subterfuge. In fact, Fuchs was recruited to work in the Theoretical Physics Division by Hans Bethe (Gustaf Skarsgård). Also unaware of Fuchs' outside loyalties, Bethe eventually lamented Fuchs in Richard Rhodes' book, Dark Sun: The Making of the Hydrogen Bomb, as "the only physicist he knew to have truly changed history" because of the assumption that his imparted fission data helped accelerate the global nuclear arms race. In truth, that was never quantifiable because how Lavrenti Beria, the head of Russian nuclear development program, used Fuchs material was never corroborated as just outside proof of their own findings, or material that moved the Russian program beyond their own research.

The true story of Fuchs spying on the Manhattan Project

Regardless, who was Fuchs and why did he spy? Oppenheimer the film doesn't answer any of those questions. In fact, Fuchs is very much just a support figure in the ensemble of scientists in the Los Alamos section of the film, leading up to the Trinity test. But when he arrives in New Mexico, and is asked how his German citizenship had suddenly converted to British citizenship, he replies, "Since Hitler told me I wasn't German." That line refers to Fuchs' exodus from Germany in 1933 during the rise of Hitler. Fuchs was a member of the Communist Party of Germany, which made him a target for the growing Nazi Party. While in United Kingdom, he worked at the University of Edinburgh with other German scientist refugees. 

However, his Germany origins made him circumspect to the British government and thus he was interned on the Isle of Man for several months in 1940. After release, he returned to Edinburgh and in a surprise change of events, was recruited to join the British atomic bomb research project in 1941. Fuchs became a British citizen in 1942. 

Not long after, he was approached to spy for the Soviets and agreed. His initial codename was "Rest" and moved to New York to work at the Columbia University arm of the Manhattan Project which was focused on gaseous diffusion research. In 1944, he transferred to the Los Alamos National Laboratory working under Bethe. He was given the work rejected by Edward Teller (Benny Safdie), was co-author of the Fuchs-Nordheim method and did integral papers on blast waves. Present at the Trinity test in 1945, Fuchs was considered by Bethe to be one of the best theoretical physicists on the project. 

Throughout his time in New Mexico, Fuchs reported information to his American courier, Harry Gold. Fuchs stayed at Los Alamos under Oppenheimer's successor, Norris Bradbury, who personally requested he remain. But Fuchs was recruited to return to the United Kingdom to work on their nuclear program, and in 1946 became the head of the Theoretical Physics Division at the Atomic Energy Research Establishment at Harwell. It wasn't until 1949 that Fuchs work as a spy became known. He was interrogated but didn't confess his status until 1950. He was arrest that same year and charged with violations of the Official Secrets Act.

How To Stream Oppenheimer?

Oppenheimer is now streaming exclusively on Peacock alongside a slew of behind-the-scenes featurettes.

The NBCUniversal platform currently offers two monthly subscription plans: Premium ($5.99 a month with ads) and Premium Plus ($11.99 a month with no ads and download access for certain titles). If you're a student, you can enjoy the Premium plan for just $1.99 for an entire year!

Looking for some theatrical action in the meantime? The HoldoversMy Big Fat Greek Wedding 3The Exorcist: BelieverFast XRuby Gillman, Teenage KrakenFive Nights at Freddy's, and Strays are all streaming on Peacock!

Originally published Jul 22, 2023.

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