Named in the Venona Project (A lot of publications have no rebuttal explaining this away), Merkulov’s letter to Beria was suspicious as heck, was screwing a Stalinists including his wife (Sorry, no ideological escape back then of separating Communist from Stalin despite that asinine Emily Blunt’s cross-examination scene), good friends with Stalinists, Manhattan Project had a load of leaks (Wasn’t just Fuchs) to the USSR (From what was said by former Soviet officials, and Robert Downey’s character wasn’t joking when he stated the rapid intensification Soviets had in developing the A-bomb in which the US should go full bore on the H-bomb (Since Soviets were doing the same thing). Movie was made well but the material was bad propaganda. Heck of a theoretical physicist though.