They should not have been playing war in a war zone. The US pilot was under the idea it was hostile fire and responded as trained. No blame attached to the pilot but the Canadian and US Coordination should have been comunicating with each other; obviously they did not know what forces were deployed.

Roger Miller Song.. You Cant Roller Skate in a Buffalo Herd...

You cant play games in a combat zone
But you can march in minefields if you've a mind too.