Well you are kind of right, but only in a way....and even that maybe...
Serbs did fight on the territory that was their own country named Yugoslavia (not like coalition of the "billing" in Afghanistan and Iraq or Israel in Lebanon now), they did not occupy any other foreign country, and you know there was no aggression  legally. They fought partition of their country that they made spilling blood in WWI and WWII..
Problem is that being strongest militarily they used excessive force...Why this reminds me so much of these bustards today mentioned above?