We did it for oil then*.
We're doing it for oil now.
Almost all Americans cheered our depredations then.
Almost all Americans are cheering the planned war now.
This is a democracy, we tell the world, so all Americans become responsible for the government's policy whatever its moral value.
If our policy does evil, or is even perceived to be doing evil, we are not truly innocent, and we definitely cannot expect to be perceived as innocent. In a democracy, we can't escape responsibility by accepting our individual (hugely various) amounts of freedom and prosperity, but rejecting "politics" altogether, and just voting once every year or so doesn't get us off the hook either; it's a messier business than that, but nobody said it would be easy or pretty. I notice we also show absolutely no inclination to give up our decades-long orgy of cheap oil and the militarily-enforced worldwide economic hegemony needed to support it. Think SUV.
Iraq is not a democracy, we (correctly) tell the world, so Iraqis are not reponsible for their government's policy.
There are therefore, strictly speaking, no American civilians, but on the other hand, there may, strictly speaking, be almost nothing but civilians in Iraq, even including its army, made up of men otherwise without hope or any livelihood.
The U.S. is in a very awkward position, but one largely of its own making. We have succeeded in making American civilians real and potential targets for the anger and resentment of people of other cultures, but we are unable to justify making the civilians of those cultures into our own targets, whether in Mesopotamia, Afghanistan or anywhere else in the world.
A state unable to access its military power and unsuccessful in employing its moral authority, could easily find itself disintegrating, especially if it is not able to address, or to even recognize, the needs of peoples outside. We don't seem to be doing well right now. If there is a war going on, we're not winning it.
Americans have to start operating with our minds and our hearts instead of our phalluses and our fears.
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* "During the Iran-Iraq war, the United States decided it was imperative that Iran be thwarted, so it could not overrun the important oil-producing states in the Persian Gulf." [NYTimes]