Nah, you have to be more devious. Cheap vodka is fine. Just start making lots of flights (aka the Berlin Airlift) on a regular basis over Soviet territory. Start small. A case here, a case there, "accidently" dropped. Slowly, it becomes a common occurance. Word gets around that liquor, cigarettes, chocolate, and other 'goodies' are falling out of Allied planes flying to Berlin.
Soon, the desertion rate in Soviet units rises as soldiers slip away to get their share. Units along flight corridors fall into complete disarray. Once the corruption has thoroughly taken hold then the Allies strike!