The civilians of Falluja are negotiating to stave off a threatened US-led military incursion. American military spokesmen insist that US-led forces will do their utmost to spare civilian bystanders. But if they don't, the newly free Iraqi press will have trouble reporting the story. The Iraqi Health Ministry, on orders of the US-backed government, has stopped releasing Iraqi casualty figures to journalists. The ministry's numbers had been turning up in news reports, most notably in a Knight Ridder story on how many Iraqi civilians have been killed in recent fighting, which was widely distributed in the United States.

So the problem of Iraqi civilian casualties reverberates in the troubled US military occupation of Iraq. But what isn't known about ordinary Iraqis dying from US firepower is a big part of that problem. The Pentagon shows no interest in the subject. "We don't do body counts," Gen. Tommy Franks has famously said. And in the chaos of Iraq, reporters and public health authorities simply can't keep track. This isn't just a problem for the Iraqis whose lives are at risk. It's a problem for Americans trying to figure out how the military is going to overcome the hostility it now faces in Iraq.

On the subject of civilian casualties, Americans lack what they usually love: a nice round number that endows an emotional issue with numeric authority. In September the talisman figure of 1,000 US combat deaths became the emblem of growing national doubts about the war in Iraq. But all the experts on Iraqi civilian casualties argue persuasively that there is no comparably accurate figure that might sum up the suffering of the Iraqi people.

On October 19, the New York Times took a step toward settling on a civilian casualty number by reporting that "the best estimates" of private groups and independent news organizations are in "the 10,000 to 15,000 range." That is comparable to the figure given by iraqbodycount.net, a website run by US and British antiwar activists, which gives a low estimate of 13,928 civilian deaths in Iraq and a high one of 16,053. The site's researchers carefully monitor news reports of civilians killed in warlike incidents and because of breakdowns in law and order and healthcare and sanitation problems, weed out stories that appear in only one place and add up all casualties.

Complaints about the group's reliance on media sources are overblown. The bigger problem is that Iraq Body Count's figures do not distinguish between Iraqi civilians killed by US troops and Iraqis killed by jihadists. The site's founders say that, as an occupying power, the United States is responsible under the Geneva Convention for all violence suffered by Iraqi civilians. The result is confusion. According to the Iraq Body Count methodology, if the Iraqi insurgency killed twice as many civilians as US Marines next month, all of those deaths would be chalked up to Washington's policy. That may be morally satisfying, but it doesn't really measure how US soldiers are treating Iraqi noncombatants. The Iraq Body Count number is more reliable as an index of Iraqi chaos than civilian casualties of US force.

But there's another way to gauge civilian casualties, and that is to consult not the media and not human rights groups but US troops themselves. …