Hi:
Here my "two grains of salt."
All the maps -- even the digitized ones -- and even if Russian are subject to Article 2 of the Berne Convention for the Protection of Literary and Artistic Works (that is also of maps and atlases). I'm not sure if the Russian signed them or not, BUT Russia signed the WIPO convention on the protection of IP (so even of geographic maps and atlases, digitally considered databases).
Furthermore, we have to consider that the fourth part of Civic code of Russia of January 1, 2008 on the protection of Intellectual Property has also been recognized by the World Intellectual Patent Organization (WIPO). This convention was signed in 1967 also by Russia.
As far as I know, Russian and Soviet geographic maps, atlases, geographic services, even if digital (in which case are considered databases), in full or in part, exact or counterfeit, are protected by the above mentioned laws, everywhere.
The use of Soviet maps should be possible, however I think, under "fair use" (for education).
I hope these helps.
Lucia Lovison-Golob
Geospatial Director of Afriterra Library, USA