That swings both ways really, there's a fair amount of stolen Russian loot around Europe for the same reason. I think a lot of this should be on a case by case basis. (There's also a fair amount of Byzantine art around Italy from the fourth Crusade that the greeks wouldn't mind seeing returned as well).
Didn't the Italians steal the body of Saint Nicholas from Myra, not long after the Great Schism?
The Russkis have Von Schliemann's treasure of Troy stolen from the Berlin Museum.The Nazis stole the Amber room from Caterine (was she ever) the Great(s')Summer Palace outside St Petersburg.Probably thought that since Catherine was German they had a legitimate claim.The German Government replaced /restored the Amber Room a few years back and are still negotiating for return of the Treasure of Troy.