Pri: I would respectfully point out that, in Soviet Russia, a great deal of “the horrors” were pre-WWII, including mass starvation during collectivization and the “war against the kulaks”, and mass murder during Stalin’s Great Terror and Red Army purges. Millions either starved to death (largely Ukrainians and ethnic Poles) or were put to death following Soviet “show trials”. The killings continued through WWII, and now included those perpetrated by Hitler and the German war machine, after they invaded the USSR in 1941.
We can’t use China during WWII, because Communist China didn’t come into being until 1949, when the Nationalists fled to Formosa (Taiwan).
To say that the Coommunists were stronger than ever, then, is also incorrect. Yes, the Soviets did foment insurgency and insurrection throughout the world, mainly in the form of National Liberation Fronts (like the Viet Cong), but that wasn’t fully felt until the 1960s. The Soviets didn’t fully recover from WWII until the mid- to late-1950s.