Why indeed. I was wondering about that - whether the Americans knew that Giuliana had been released and was being transported to the airport. I felt certain they would have been. So, my original thought - that she's an independent reporter in Iraq, and one for a Communist news source at that - still niggles...after all, there are plenty of other incidences in which the U.S. has targeted journalists in Iraq.
And not something the Italian secret service and a reporter wouldn't know, making that a highly questionable scenario. At any rate, it's not true for another reason. The reporter (and presumably the other agents in the car) say there was no checkpoint.
Update 8:00 pm:
My only question about the intention to kill another journalist would be that they should not have left anyone alive to tell the story. It may be in this case simply that this was the action of another bunch of trigger-happy soldiers.
Somebody's ass is going to be in a sling, one way or another, and any future similar incident won't have any survivors.