During the Great War, the German government covertly supported Lenin and the Bolsheviks, to an extent, in order to ferment discord in Russia. Ultimately, this led to the Russian Civil War and Bolshevik victory.
However, if the Central Powers ended up winning in the west (no US entry, for the sake of argument), would they be strong enough, or even willing, to take on Soviet Russia to the extent that the Allies did as OTL? Would even the Allies, war-weary and defeated after a (presumably longer) war, contribute in any meaningful way?
In short, what would it take to have a Soviet Russia in existence after a CP victory?