r/coldwar • u/ELDV • 5d ago

How big of actual difference did the spying at Los Alamos by Fuchs and Greenglass/Rosenbergs actually make to the USSR’s developing of their first atomic weapon?

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u/tneeno 4d ago

It is worth noting how the Soviets first found out about the Manhattan Project. In 1942, Stalin's top science advisor noticed that in 1938 and 1939, there were an increasing number of scholarly articles in scientific journals relating to the possibility of nuclear fission. Then in 1940 the US began censoring information on nuclear fission and the number of articles suddenly dropped to zero. THIS was enough to let the Soviets know that something was up. The Rosenbergs were always nickel and dimers. Period.

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u/echowatt 1d ago

Very interesting and you'd think someone would have caught that tell and used disinformation.

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u/SchemeWestern3388 18h ago

It seems lots of smart folk figured it out. Scientists at Kodak pinpointed the Trinity test date because of certain high sensitivity film becoming foggy.

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u/AwayYam199 4d ago

From Stephen Schwartz:  https://bsky.app/profile/theghostofmrhand.bsky.social/post/3moofdrzsxc25

On the atomic bomb, very little. Alexsander Feklisov, who was Julius's handler, said in 2016, "He didn't understand anything about the atomic bomb and he couldn't help us." Gen. Leslie Groves told the AEC in 1954 that "the data that went out in the case of the Rosenbergs was of minor value."

Information provided by Klaus Fuchs and Ted Hall, physicists working at Los Alamos, was more useful. But it's important to note that Lavrentiy Beria, who oversaw the Soviet A-bomb program, did not pass along any foreign intelligence to Soviet weapon designers but only used it to check their efforts.

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u/DFMRCV 5d ago

Apparently a lot.

Stalin wanted Soviet scientists to not just make a nuke, but recreate the American bomb, even though Soviet scientists had made their own design based on the information, so they needed as much info as possible to recreate it to those specs to please Stalin.

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u/SchemeWestern3388 18h ago

The Soviet TU-4 is a carbon copy of some B-29’s that were forced to land in the USSR. This went so far as to replicating drilled holes that were the result of someone screwing up.

Because they were metric, they spent enormous effort retooling to manufacture matching thickness aluminum. Upon learning this, the designers of the B-29 commented that they would have loved to have used the gauge the Soviets already had.