I would guess that the "Russian trolls" would say that that wasn't stolen by the official Russian army, rather by Russian people who are fighting in Ukraine.
As far as I am aware, no one debates the fact that Russians have been fighting in Ukraine, what is debateable is if the Russian army has been fighting in Ukraine (whilst on duty, thus paid to do so by Russia)

It's not quite as easy to define as you would think!

Still, someone in a position of authority should get this monument back to Ukraine.