The Soviets might not have perfected an A-bomb before the early 1950s had it not been for help from espionage.
Ergo, the Soviets might not have permitted the Korean War to be launched, since they would have had no retaliatory weapon ready. and the US would have had a monopoly on the Bomb.
So, it is possible that all the deaths in that war (Korean, US, and others) and all the destruction, were the result of espionage by many —including the Rosenbergs.
Not to mention all the millions murdered by the North Korean regime over the years.