The leftist spies meant the Soviets got the Bomb more quickly than they otherwise would have.
If there had been no leftist spies they would still have gotten it, would have just taken a little more time.
Unless you believe the laws of physics aren’t as accessible to commies as to anybody else.
...or to Nazis.
If Hitler had found the genie first....
And if NOBODY had found the genie, then WWII would've turned the Pacific red, and the cold war would have gone hot conventionally in the 50's and devastated half the planet.
But there were leftist spies like the Rosenburgs and they did change the course of history.
What if, what if, what if.....
Kurchatov was independently reaching the same conclusions. The spy ring merely confirmed that he was on the right path, thus likely cutting the Soviets’ development time significantly.
Sakharov’s “dry” H-bomb, however, was developed independently.
Interesting little thing about Soviet nuclear development. In the early stages, nuclear weapons development was overseen by the NKVD/KGB, notably, Lavrenty Beria. Kurchatov was doing a demonstration run with the equivalent of Chicago Pile One, when Beria was present. The radiation counters were very active, however, Beria was complaining that he could not here anything, or feel any building vibration. Thus he thought Kurchatov was trying to pull a fast one, and maybe Kurchatov would have wound up in the GULAG. Beria nearly stormed into the room where the graphite pile was operating, but was prevented from doing so by the other scientists. If Beria had succeeded from entering the room, he would have been cooked by the radiation flux.