I read the link, Huan Yi. I'll understand your question as an authentic cry of outrage and confusion. For myself, the outrage and confusion begins earlier, with the question of why anybody thinks they have a right to kill anybody else. I don't think there's much of a justification
for any of it in the middle east or elsewhere. I'm odd that way and pretty much have always been so.
Once people think killing is a legitimate way of solving problems, ever more outre solutions present themselves as rational.
However you can't be very interested in pacifism as a philosophical life-position. There are areas in it that give me trouble as well.
This is the way resistance movement operate. They certainly operated that way in France and in Europe during World War II. When Heydrich was assassinated outside Lidice by Czech partisans, the underground knew the Nazi policy of retaliation against local populations. The death of the village was a steep price to pay (and then some, if I remember my history). The partisans are remembered today as heros, the villagers as martyrs.
How do we understand this? We understand this as business as usual. Because we are on the other side, we are shocked and disgusted at the sheer inhumanity of it all. (It IS inhuman. It IS disgusting. Any death diminishes me.)
The Green Zone, though, is supposed to be protected, safe U.S. grade A property; and those inside are supposed to be more or less immune from the chaos the rules outside. If you wanted to send a message to people who thought they were your conquerors (in your own point of view) what better place? The civilians there, to your mind, would probably be collaborators— what better targets?
The green zone, because of it's concentration of U.S. military and diplomatic personnel and Iraqi collaborators
certainly does seem to make it an appropriate target.
Pardon me, Huan Yi, but are these guys supposed to love us for occupying their country? This isn't an instance of going after civilians in the street near as I can tell from the link you supplied.
And where was your upset about going after people in the street when we were imprisoning and torturing people in prisons in Iraq who were there on little or no evidence at all. Who were literally people in the street? How do you feel about the humiliation and torture of innocent people for information they don't have? To gain dubious information that won't stand up in court.
As a matter of personal curiosity, Huan Yi, because it's information I don't have, do you know how the information gotten by torture of most of these people has been graded by the NSA and the CIA for reliability?
I would be very interested to know that if there was a trustworthy source who could let us know. Without a political axe to grind one way or the other.