The best response to this particular claim is to ask for proof, and then make your judgement according to the response.
Try it, it's fun.
"The Sebs I did meet on patrol were helpful once they discovered we ment them no harm. I wasn't in a position to make friends. With the Croats and Muslims doing their stuff I was in a volitile situation where anyone can start a fire fight over anything. The Croats and Muslims concerned me more then the Serbs."