Reaction to the stunning 2007 footage from Baghdad has only begun. For some of the Atlantic's interpretations, see for instance here and here

But one of Andrew Sullivan's commenters raises a point I meant to make previously -- and which, because it was the middle of the night, I didn't spell out. What I said was: as with Abu Ghraib, there will be a strong temptation just to blame (or exonerate) the lower-level people who pulled the triggers, but that deflects us from real questions of responsibility.

There will be  lot of those "real questions" to consider, from rules of engagement to the apparent cover up of the footage. But the threshold point I meant to start with is this: The very high likelihood of such "tragedies" occurring is a very strong reason not to get into wars of this sort

By "of this sort" I mean: twilight-zone urban warfare, not to mention "discretionary" or "preventive" wars, and situations in which a heavily armed-and-amored occupying force of foreigners tries uneasily to mix with a population overwhelmingly of a different race and religion and language. For their own survival, the occupiers need to be hyper-suspicious and ever alert -- even though today's prevalent Counter Insurgency doctrine ("COIN") warns of the self-defeating consequences of behaving this way. (Indeed, a mounting debate about the COIN approach in Afghanistan is whether the effort not to seem distant from the local population is exposing US soldiers to too much risk.) It is a situation with enormous potential for miscalculation, misunderstanding, and tragedy. And therefore one to avoid if you have any choice at all.

It is right to be shocked at the violence in this footage, as we are shocked when an especially hard hit in a football game leaves a player motionless on the field. But the violence behind that hard hit is one millimeter away from what the football players are praised and rewarded for doing. The decision to gun down Iraqi civilians in real-time pressure and ambiguous circumstances ("Is that a gun?" "Are they hauling a wounded terrorist away? Can we get clearance to 'engage' right now????") is one millimeter away from the alert and aggressive warrior spirit for which troops are honored and trained. Ideally, every warrior would always know the exact line that separates just enough violence from too much. They can't know that in real time, which is why no war, even the most necessary and justified, has ever been "clean."

We could not know that this episode would occur. But we could be sure that something like it would. It's not even a matter of "To will the end is to will the means." Rather the point is: You enter these circumstances, sooner or later you get these results.

A failure of tragic imagination is what I most criticized in war supporters in the months leading up to the invasion of Iraq, and it was much of the reason I opposed the war. We can't do anything about that decision now. But this new footage is worth bearing in mind as we face the next decision -- about bombing Iran, let's say; or extending the anti-Taliban fight into Pakistan; or how long to remain in Afghanistan.

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