'A Compassionate Spy' Follows an American Physicist Who Gave Atomic Bomb Secrets to the Soviet Union

When Christopher Nolan's much-anticipated "Oppenheimer" hits theaters, his story about the "Father of the Atomic Bomb" might include a footnote about Theodore Hall. Hall was the youngest physicist working on the Manhattan Project, the American research project to build a nuclear weapon during World War II.

Hall was only 18 in 1944, when he was recruited to help discover the critical mass of uranium and work on the implosion mechanism for the plutonium bomb. In less than a year, with the end of the war in Europe in sight, the Manhattan Project's scientists knew Nazi Germany would never be able to create a bomb. Hall began to worry that American dominance with the new weapon could be dangerous.

He decided to help the Soviet Union develop its nuclear weapon by passing on the Manhattan Project's secrets to the USSR. Magnolia Pictures' documentary, "A Compassionate Spy," from two-time Academy Award nominee Steve James ("Hoop Dreams"), follows Hall's journey from teenage prodigy to atomic spy.

On July 16, 1945, the U.S. detonated "Trinity," the first-ever atomic weapon explosion, in New Mexico's Jornada del Muerto desert. Most of the Manhattan Project's staff were elated. A few, however, didn't want to join the party. Some believed that an American monopoly on atomic weapons could lead to repeated uses of the weapon or worse: a nuclear catastrophe.

Hall and several other key scientists and engineers, worried the United States could devolve into a fascist state, began handing over classified nuclear secrets to the Soviet Union. Experts believe the Soviets would have created a nuclear weapon without their help, but the espionage sped up their work by several years.

The main reason he did it, according to his own interview in the documentary: "Compassion."

Hall was not the most devastating spy in the Manhattan Project, but he provided the process necessary for purifying plutonium and handed over the specifications for the "Fat Man" plutonium bomb the Americans dropped on the Japanese city of Nagasaki. He worked for the USSR under the code name MLAD (meaning "young") until 1945, when he returned to Harvard.

After the war, Hall was not suspected of being a Soviet asset. He finished a master's degree and a doctoral degree at the University of Chicago. It was in Chicago where he met his wife, started his family and began his civilian scientific career. That career took him into the field of electron microscopy, and he moved to England to take a job at Cambridge.

He didn't know that the FBI's counterintelligence operations had caught on to some of the other Soviet spies working on the Manhattan Project. He didn't even know there were other spies in the project. Using secretly decrypted Soviet communications, the United States caught atomic spies Klaus Fuchs, Alan Nunn May and Julius and Ethel Rosenberg, among others.

Some of the intercepted Russian cables implicated Hall, but the information was withheld by the U.S. government, because they didn't want the USSR to know they'd broken Soviet codes. Hall was never tried for spying. He died in Cambridge, England, in 1999 at age 74.

"A Compassionate Spy" is a documentary thriller that follows the life of Theodore Hall from Harvard, through the war and his espionage years and into his later life, all through the eyes of his wife, to whom he admitted his crimes during their marriage.

The film will be released in theaters and on demand Aug. 4, 2023.

-- Blake Stilwell can be reached at blake.stilwell@military.com. He can also be found on Twitter @blakestilwell or on LinkedIn.

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