http://www.techcentralstation.com/030705H.html
""It's a common occurrence in Iraq: A car speeds toward an American checkpoint or foot patrol. They fire warning shots; the car keeps coming. Soldiers then shoot at the car. Sometimes the on-comer is a foiled suicide attacker, but other times, it's an unarmed family.

"As an American journalist here, I have been through many checkpoints and have come close to being shot at several times myself. I look vaguely Middle Eastern, which perhaps makes my checkpoint experience a little closer to that of the typical Iraqi. Here's what it's like. You're driving along and you see a couple of soldiers standing by the side of the road - but that's a pretty ubiquitous sight in Baghdad, so you don't think anything of it. Next thing you know, soldiers are screaming at you, pointing their rifles and swiveling tank guns in your direction, and you didn't even know it was a checkpoint. " "

"[] the rules of engagement are themselves secret."