He claims to be an infantryman, that the US is liberating Iraq, and that Osama wants the "Leftocrats" and Kerry to win. In some blogs I've read, this guy's post is being represented as an explaination from an activist point of view, but it's pretty clear that he is a troll and probably fabricated the the facts that he presents.

I think the tanks were most likely there to intimidate and to test the reaction of the public. They don't have to be in a position to fire to do this.