Degas' doodle of boudoir melodrama is the worst kept secret wherever it's hidden.

Russian soldiers found the painting stored in the Pergamon Museum in the wake of World War II and figured finders=keepers. After all, the Nazis had looted unknowable numbers of artworks on their foray into Soviet territory, and the Russians wanted to dish out some of that in return. Today, Germany claims Interior and the other looted works should be returned. 

Russia's deflected the request by saying Germany has no claim to the art since it was taken from Nazi Germany #smartasses. The reply is mostly shifty eyes, however, when the Russian government is confronted with the fact that most of the art was taken from private German collections. Shifty eyes and silence: the best way to avoid an awkward conversation. Interior, for instance, was stolen from Germans who didn't even like the Nazis. 

When the Russians plucked Interior from the Pergamon's basement, little did they know they were stealing from poor, poor Friedrich Siemens. Emotionally poor, since his painting was stolen. Financially loaded, since his family owned the Siemens corporation. Friedrich's family were none too pleased with the Nazi way of business, but only became targets of the regime when his brother-in-law tried to kill Hitler. If you've seen Valkyrie with Tom Cruise, you know the story, because Tom Cruise's real life counterpart from the movie, Claus von Stauffenberg, was Friedrich's brother-in-law. 

So, after Claus [SPOILER ALERT] tried to blow up Hitler like an idiot (for real, the movie's an exercise in patience for anyone with a brain stem), the Siemens family went into lockdown mode. Friedrich didn't want Hitler's grubby Vienna sausage fingers all over his lovely paintings, and he got Stalin's borscht-tainted fingertips instead. I'm willing to chalk it up to schadenfreude.