There's a whole regiment of immigrants who worked on the Manhattan project, as we all know. We also know that the USSR obtained much of their knowledge on how to build the bomb through espionage.

Espionage? Gasp. The US would never do that to get ahead. I'm so suspicious of claims without external sources of provenance about American exceptionalism during the cold war that I take all if it with a large grain of salt. Back then, everything Russia said was propaganda, and everything the US said was truth from the mouth of god.