Venona Project was a gold mine for sure. I think The Mitrokhin Archive (The Sword and the Shield in the US) had more revelations though. It was released around the same time, but not published until 1999. Something to keep in mind, the Russians were accomplished spy experts for decades before WW2. The US did not have a spy department. The Roosevelt administration had numerous Russian spies, which ultimately led to various assessments and heightened paranoia about the "red scare".

Venona confirmed the Rosenberg's affiliation with Russia. However, it also confirmed Theodore Hall provided the most detailed and complete information, including specifications for a complete device. Hall was never prosecuted. Hall's older brother Edward was the father of the inter continental ballistic missile (ICBM) program.

Charlie Chaplin ran into this. He associated with numerous communists, attended Russian social events, and was effectively deported from the US in 1952. His granddaughter, Oona Chaplin is a bit salty about this in her documentary "Hollywood Exiles", but the reality is he wasn't a US citizen so it probably wasn't a good idea to consort with the Russians while living the US.

https://en.wikipedia.org/wiki/Mitrokhin_Archive

https://en.wikipedia.org/wiki/Atomic_spies

https://en.wikipedia.org/wiki/Edward_N._Hall

https://en.wikipedia.org/wiki/Charlie_Chaplin#1939%E2%80%931...