I was looking to watch a Soviet movie from the 1970's (Moscow-Cassiopeia, nothing with much communist propaganda, just a teen comedy). I thought that this movie would be only possible to find through torrent sites, but I was surprised to see it for sale on iTunes. Who would be Apple licensing this movie from? There was an embargo against Soviet Union during the 1980's, wouldn't have this disabled any copyright from before this embargo?
The Soviet Union generally had no copyright treaties with the western world before 1973. So, anything before then is public domain. The USSR had a policy of public domain and considered anything published to be the property of the "people", including anything published in the west.
Even for works produced after 1973, they would have to be registered for copyright in the United States to claim a copyright here.