It was a NATO peacemaking operation.
Russian troops should not have even been there in the first place. Especially taking into consideration of the facts about persons like Strelkov. And as far as I recall, the Russian military leader bypassed the proper chain of command and were acting not like peacekeepers, but like allies of Serbia.
Russia can go and feel her own bottom.
The Russians, who played a crucial role in persuading Yugoslav President Slobodan Milosevic to end the war, had expected to police their own sector of Kosovo, independent of Nato.
When they did not get it, they felt double-crossed.