Soviets killed Americans in the form of shooting down some planes. Also the CSA were Americans too, so is the Union just as terrible for killing Americans? Read any history book, both sides are Americans, that's why the civil war killed the most Americans of any war, because it did it at twice the pace. Well, let's be honest, the CSA only threatened freedom for blacks. Still not good, but it didn't threaten freedom for all men. Communism on the other hand is by nature bent on global domination, it's part of the Communist manifesto, and it eradicates the freedom of every man, white, black, asian, etc, because you are now under total control of the state.
Oh and the Soviets killed tens of millions of their own via starvation, etc.