New Report Unmasks Fourth Spy at Manhattan Project

Oscar Seborer eventually left the United States for Russia

Manhattan Project sign
The Manhattan Project abounded with signs emphasizing security.
US Department of Energy/Creative Commons

The history of the development of the atomic bomb remains a subject that captivates us today. But the scientific initiative it took to create the device and the moral debates that surrounded its use aren’t the only elements of its history that still resonate with us today. The story of the Manhattan Project is also inexorably connected with the nuclear arms race that ran throughout the Cold War — and that involves unsettling stories of espionage.

Now, a new element of that history has come to light: an article at The New York  Times tells the story of the fourth man who spied on the Manhattan Project in Los Alamos on behalf of the Soviet Union.

William J. Broad, who has shared two Pulitzer Prizes for this work, has the details. The initial details on the spy, named Oscar Seborer, came from a report in the CIA journal Studies in Intelligence that was written by Harvey Klehr and John Earl Haynes, both experts in their field.

Seborer was codenamed Godsend and, according to the article, he was not the only spy in his family. Broad writes that “[i]n 1951, Mr. Seborer fled the United States with his older brother Stuart, as well as his brother’s wife and mother-in-law, and defected to the Soviet Union.” Seborer lived there until his death in 2015. 

Some of the specifics of Seborer’s espionage remain classified, even now. But the account that Broad has documented is a fascinating read; it also, as its author notes, has more than a few resonances with current tensions between the United States and Russia. 

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