The Sleepy Israeli Town and the Jewish Spy Who Helped the Soviets Get the Bomb

Newly declassified CIA information reveals the story of Oscar Seborer, who gave the Soviets vital secrets to help them develop their own atomic bomb, and whose parents are buried in Gan Yavne

Ofer Aderet
Ofer Aderet
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The inscription on the grave of Abraham Leib Seborer in Gan Yavne, southern Israel.
The inscription on the grave of Abraham Leib Seborer in Gan Yavne, southern Israel.Credit: Gidi Poraz
Ofer Aderet
Ofer Aderet

The tombstones of the parents of an American spy who reportedly leaked vital nuclear secrets to the Soviet Union in the 1940s were recently uncovered at a cemetery near Ashdod, southern Israel.

At Haaretz’s request, Gidi Poraz – a genealogical researcher who searches for missing Jews around the world – located the graves, which had not been tended in a long time, in the small town of Gan Yavne. He cleared the weeds and cleaned the tombstones before photographing them.

The Hebrew inscription on the tombstone of Abraham Leib Seborer, who died in 1971, reads “Ben Torah VeYashar Derekh” (“A righteous and just man”). The tombstone of his wife, Shaina Brucha, known as Jennie, who died in 1964, bears no special inscription.

Finding these graves was no simple task. The religious council at Gan Yavne, a town founded in 1931 by Jewish families from the United States, does not keep a registry of graves. The man responsible for the cemetery, who was born and raised in the town, insisted that he “remembers everyone” and that “there is no Seborer family.” But Poraz, armed with information from the FBI that was published in The New York Times, did not give up.

Following the discovery of the graves, the local council may want to update its official website about the small sleepy town’s history and add a new chapter on the incredible, James Bond-esque tale of Oscar Seborer.

It was revealed last fall that he was one of four spies who leaked information to the Soviets about the secret mechanism used to activate the atom bomb that was dropped on Nagasaki, Japan, on August 9, 1945. His actions helped launch the Cold War and almost triggered a nuclear Armageddon in the early 1960s.

Jennie Seborer's grave in Gan Yavne. Found after much sleuthing by genealogical researcher Gidi Poraz.
Jennie Seborer's grave in Gan Yavne. Found after much sleuthing by genealogical researcher Gidi Poraz.Credit: Gidi Poraz

Code name: Godsend

“The story of Gan Yavne is one of creating something from nothing, and part of the revival of the Jewish people in its homeland. Gan Yavne was founded on pasture land of the Arab village of Baraka by Ahuza Alef New York, a company founded by several Jewish families from Russia, Poland and Central Europe who immigrated to the United States,” the local council’s website grippingly relates.

Now the story of one of those families, the Seborers – who made their way from Poland to the United States and later to Gan Yavne – may also be told. One of their sons, Oscar Seborer, worked on the Manhattan Project, where America’s atomic bomb was developed, and is suspected of having spied for the Soviets using the code name Godsend.

Documents recently uncovered in the United States and published in the CIA journal Studies in Intelligence last September indicate that he had “an intimate understanding of the bomb’s inner workings” and “played a crucial role in Moscow’s ability to quickly replicate the complex device,” the New York Times reported in January.

A U.S. nuclear historian noted in the same article that Seborer had unusually broad professional knowledge and that the information he stole “could have been unique.”

Abraham Seborer and his wife Jennie were born in Poland in the late 19th century – Abraham in the city of Przasnysz and his wife in Maków Mazowiecki. Their eldest son Max was born in 1903. The young family immigrated to Great Britain, where their son Noah was born two years after Max. Around 1909, they moved on to the United States and settled there. In 1918, another son, Stuart (originally Solomon), was born, followed by a daughter, Rose, in 1919. The youngest son, Oscar, was born in 1921.

Scientists and workmen rigging the world's first atomic bomb at the Trinity bomb test site in the desert near Alamagordo, New Mexico, July 1945.
Scientists and workmen rigging the world's first atomic bomb at the Trinity bomb test site in the desert near Alamagordo, New Mexico, July 1945.Credit: AP Photo

Like many Jewish immigrants from Eastern Europe, the Seborers did not have a higher education but all of their children, with the exception of Rose, did go to college. In 1934, Abraham and Jennie Seborer immigrated to British Mandatory Palestine. According to information published on the CIA website, Oscar apparently joined them there. However, four years later, in 1938, the Seborers returned once more to New York.

The Seborer siblings supported the Communist Party in the United States, though not all of them officially became members. According to the CIA, the whole family was “part of a network of people connected to Soviet intelligence.”

Max married a series of women who had ties, directly or indirectly, to communist espionage; Noah was a party member; Rose worked in various administrative positions for the party in New York; Stuart went to City College of New York with Julius Rosenberg – the Jewish “atomic spy” who along with his wife Ethel was executed by the Americans in 1953 – and was surrounded by party members, though he did not officially join the party himself.

The blueprint of Fat Man, the atomic bomb that the United States dropped on Nagasaki on Aug. 9, 1945.
The blueprint of Fat Man, the atomic bomb that the United States dropped on Nagasaki on Aug. 9, 1945.Credit: LOS ALAMOS NATIONAL LABORATORY /

Oscar attended the same New York college, which was later described as a hotbed of communist activity. In 1942, he enlisted in the U.S. Army. Because of his technical abilities, he was assigned to the Manhattan Project – the code name for the development of America’s first atomic bomb. Initially, he was posted in Oak Ridge, Tennessee, the site of the Manhattan Project’s production plants and uranium enrichment facility. In 1944, he was transferred to the National Laboratory at Los Alamos, New Mexico, where he worked in nuclear weapons development until 1946.

On July 16, 1945, he was present at the Trinity test – the first detonation of a nuclear device in history, when the efficacy of the bombs was tested prior to being used a month later. The objective was to measure the seismographic impact of the blast.

After the war, Oscar earned an engineering degree at the University of Michigan and was hired to work on secret research projects for the U.S. Navy. But in 1951 he lost his job when he was found to have ties to communist activity, although there were no solid suspicions against him of committing espionage.

On September 3, 1951, he arrived in the nascent State of Israel with his brother Stuart, who had also come to be suspected of communist activity. The two visited their parents, who had returned to Israel from the United States the previous year and now lived in Gan Yavne. Their brother Max also obtained a visa to visit Israel at that time, but it is not clear if he used it.

Studies in Intelligence reported last year that “the FBI has known since 1955 that Oscar, his brother Stuart, Stuart’s wife Miriam, and Miriam’s mother all secretly defected to the Soviet bloc in 1952, living initially in East Germany but then moving to Moscow, where they lived under the name Smith.”

The grave of Abraham Seborer in Gan Yavne, found and restored by Gidi Poraz.
The grave of Abraham Seborer in Gan Yavne, found and restored by Gidi Poraz.Credit: Gidi Poraz

Oscar died in Moscow in 2015 and Stuart, in a wheelchair, was present at his funeral. Oscar’s daughter Genia Smith (Seborer), did not respond to a request from Haaretz for more information about her father.

In recent months, members of the Seborer family have emerged from hiding to become “big names” around the U.S. intelligence agencies. It started last year when historians published documents indicating that Oscar Seborer infiltrated the Los Alamos labs where the first nuclear bomb was developed and delivered secrets to Moscow concerning the Manhattan Project. The labs subsequently permitted the publication of more documents, which revealed that this “mundane espionage case” was possibly “one of history’s most damaging,” as the New York Times reported in January.

During the time he worked on the U.S. nuclear program, Oscar Seborer acquired extensive knowledge about the workings of the atomic bomb. “His knowledge most likely surpassed that of the three previously known Soviet spies at Los Alamos,” the New York Times said, and the information he stole likely played a key role in helping the Soviets create their own nuclear device.

In August 1949, just four years after the nuclear test in which Seborer participated, the Soviets detonated their own atomic bomb, putting an end to Washington’s nuclear monopoly and intensifying the Cold War that would rage for the next 40 or so years.

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