VENONA PROJECT (Russian Spies)
Although the Manhattan Project was betrayed to the Soviet Union by at least a handful of domestic spies—most of them Americans, all of them dedicated communists—I have yet to encounter any documents or even anecdotal evidence which would indicate that there was any similar effort that gave US and Allied nuclear secrets to the Germans.
David Greenglass | American spy
Fourth Spy Unearthed in U.S. Atomic Bomb Project
https://www.nsa.gov/Portals/70/documents/about/cryptologic-heritage/historical-figures-publications/publications/coldwar/venona_story.pdf (https://www.nsa.gov/Portals/70/documents/about/cryptologic-heritage/historical-figures-publications/publications/coldwar/venona_story.pdf)
David Greenglass and His Sister and Brother-in-Law, Ethel and Julius Rosenberg, Were Among the Most Important American Spies Who Gave Above Top Secret Information About the Manhattan Project to the Soviet Union. Discovered by American Counterintelligence, Greenglass Testified Against the Rosenbergs in Exchange for Partial Immunity. As a Result, He Was Imprisoned While His Sister and Her Husband Were Executed.
However, the Germans themselves, with help from their Japanese and especially Spanish fascist allies, probably achieved a partial penetration of the Allied atomic bomb enterprise through an international spy network. This operation was launched at the behest of Baron Hiroshi Oshima, the top Japanese military attache officer in Europe, in response to the loss of Japanese intelligence assets (spies) in America following President Roosevelt’s Executive Order 9066. In the aftermath of the American crackdown, Oshima approached the Abwehr, then the primary intelligence agency in Nazi Germany, and the Abwehr in turn enlisted the help of the notorious Spanish Falangist, Angel Alcazar de Velasco.
Baron Oshima – Pacific Paratrooper
Un novillero al servicio de nazis — “A Bullfighter at the Service of the Nazis”
WWII Spanish Spy Angel Alcazar de Velasco
Japanese Baron and General Hiroshi Oshima
According to several sources, including de Velasco himself, the Spaniard proceeded to set up a spy network that was truly global in its reach. With help from a number of assets in both North and South America (including future Argentine dictator Juan Peron), de Velasco appears to have had some success in penetrating the eastern branch of the Manhattan Project, the Clinton Engineer Works at Oak Ridge, TN. This end of the Allied atomic enterprise was the one responsible for building the gun-type U-235 fission bomb that fell on the Japanese city of Hiroshima in August, 1945. If de Velasco and at least one major declassified US primary source FBI file can be believed, his operation probably gleaned at least the basics of the American approach to building an actual, functional, real world atomic bomb. The Spaniard further claimed to have given a report on what he had learned to Hitler himself.
William Pellas's answer to What did the Japanese and German intelligence achieve?
The gradual release of millions of previously secret papers in recent years has resulted in a minor revolution in WWII historiograpy. A number of widely held assertions and conclusions reached by many historians in the first decades following the end of the conflict have come in for significant reassessment and even, occasionally, rejection, in light of the information contained in these documents. Although to my knowledge none of these specifically name any Americans as Nazi nuclear agents, surprises continue to emerge from national archives in Russia, the United States, Germany, and the United Kingdom. Thus the existence of spies in the Manhattan Project whose loyalty was to Hitler and the Third Reich rather than Stalin and the Soviet Union cannot yet be ruled out.
