On my way out of Kosovo last month, I stopped off in the southern Serbian city of Nis. I wanted to find out what Serbs thought about the war that had been waged in their name, and how they felt about the atrocities committed by Serbian forces against ethnic Albanian civilians. My first call was on the mayor, Zoran Zivkovic, a leader of Yugoslavia's Democratic party and a longtime opponent of President Slobodan Milosevic.

While Zivkovic certainly did not condone the killings of ethnic Albanian civilians in Kosovo, he was more interested in talking about killings he had witnessed within sight of his own office. On two occasions during the war--on May 7 and May 12--NATO warplanes dropped cluster bombs on the center of Nis, killing a total of 15 civilians. (NATO maintains that both times it was trying to hit the airport, several miles away.) I asked Zivkovic which was worse: a NATO pilot unloading cluster bombs or a crazed Serbian paramilitary fighter gunning down fleeing refugees. As mayor of Nis, he said, his primary concern was "the suffering that NATO has caused to the people of my town."

Having spent much of the previous week examining mass grave sites in Kosovo, and finding incontrovertible evidence of Serbian war crimes, I was in no mood for lectures on "NATO atrocities." On reflection, however, I think Zivkovic raised a profound point about America's reliance on air power in waging war, and one we need to think about carefully. Over the past 50 years, America's increasing technological superiority has enabled us to engage in warfare without directly confronting our victims. In so doing, we have also placed extraordinary value on preserving the lives of our pilots, sometimes at the possible expense of civilians on the ground. Kosovo is a case in point. Unlike the Serbian paramilitary troops, American pilots did not set out intentionally to murder women and children, and could not see the faces of the people they killed. But from the point of view of the victims, the end result was much the same.

Justified outrage at Serbian atrocities in Kosovo does not exempt NATO--and the United States in particular--from carefully examining its actions during the 78-day bombing campaign of Yugoslavia. Quite the opposite. As a democracy committed to upholding international law, we have an obligation to hold our own side to even higher moral standards than those we impose on others. One does not have to be an apologist for Milosevic to be disturbed by some of the methods employed by NATO in order to win its war against Yugoslavia.

Take the use of cluster bombs--a weapon used with increasing frequency as the war progressed. Made up of more than 200 individual bomblets that float down on small parachutes, cluster bombs are often used against enemy troop concentrations and armored columns. They are not precision weapons. Apart from the fact that they are relatively inexpensive, their main advantage, from a military point of view, is that a single bomb can be used to hit targets over an area the size of several football fields. But this is also their main drawback: If a cluster bomb goes astray--a statistical inevitability in a large-scale bombing campaign--the results can be devastating.

Human Rights Watch, an independent human rights organization, condemned NATO's use of cluster bombs against Yugoslavia as a violation of internationally accepted rules of warfare. A protocol to the 1949 Geneva Convention--negotiated in 1977 but never ratified by the United States--prohibits "indiscriminate" methods of combat or attacks that cannot be "limited" to military objectives (Article 51, Protocol 1).

A further objection to cluster bombs is their high failure rate. According to NATO figures, 1,100 cluster bombs were dropped on Yugoslavia during the course of the campaign, approximately 40 percent on Kosovo and 60 percent on the rest of Serbia. Working from a conservatively estimated failure rate of around 5 percent, this means there are probably at least 11,000 unexploded bomblets scattered around Yugoslavia. The objects--each about the size of a soda can--constitute a continuing danger to soldiers, civilians and children, who are attracted to the brightly colored cans. Last month, two British Gurkha soldiers in Kosovo were killed as they were attempting to defuse the remnants of a cluster bomb that fell on a school.

The Geneva Convention and other international laws codify rules of warfare that have evolved over the centuries in an attempt to spare civilians. NATO strongly denies deliberately targeting civilians--and there is no evidence to suggest otherwise--but it is obvious to anyone who visited Serbia during the war that undermining civilian morale formed an essential part of the alliance's war-winning strategy. Milosevic was unlikely to raise the white flag as long as he had the political support of the Serbian population. To erode this support, NATO gradually expanded its campaign to go after factories, water supply systems, heating plants, television stations and electric power grids, which most people would regard as predominantly civilian targets. When I asked Pentagon spokesman Ken Bacon to speculate on the reasons for Milosevic's surrender, the first factor he mentioned was "the increasing inconveniences that the bombing campaign was causing in Belgrade and other cities."

The key test for the Pentagon in selecting a civilian target was whether it could be described as "dual use." Hitting an electric power grid primarily benefiting civilians was legitimate as long as it could be said to contribute in some way to Milosevic's "command and control system." As the campaign wore on, NATO planners stretched the definition of dual use to the point where Serbs joked darkly that even bread shops had become a potential NATO target, "as soldiers also eat bread."

According to a strict interpretation of the Geneva Convention, many of these targets would be out of bounds. The 1977 protocol (Article 85) prohibits attacks that result in "an excessive loss of life or injury to civilians, or attacks on undefended or demilitarized areas"--a definition that would appear to preclude attacks on buildings in downtown Belgrade or other Serbian cities. "The general rule is that you do not jeopardize civilians if there is any way to avoid it," says Washington lawyer Walter J. Rockler, a former U.S. Marine who prosecuted Nazi war criminals at Nuremberg.

In some ways, NATO's campaign against predominantly civilian targets was more effective than its campaign against military targets. It was much easier for NATO to hit a fixed target such as a bridge or a factory than a movable--and often camouflaged--target like a tank. Having traveled extensively around Serbia and Kosovo, I am reasonably confident that the number of Serbian civilian casualties was significantly higher than the number of military casualties. The official Serbian figure for their military casualties--576--may be too low, but NATO estimates of between 5,000 and 10,000 Serb soldiers dead are almost certainly too high. The Pentagon has pointedly refused to endorse this estimate and has refrained from issuing its own figures. My estimate, based on extrapolations from independent sources, is perhaps 1,600 civilian and 1,000 military casualties. (NATO estimates of as many as 10,000 Kosovo Albanians killed by Serbian forces and buried in mass graves seem reasonable to me, if a little on the high side.)

Some of the civilians killed by NATO died in attacks on factories or television stations--targets that can reasonably be described as "civilian." Others were killed in a string of embarrassing errors, ranging from the bombing of an ethnic Albanian refugee column in Kosovo to the mistaken targeting of the Chinese Embassy in Belgrade. The Pentagon has acknowledged 20 cases in which bombs or missiles went astray and killed civilians and another 20 cases in which the missiles hit the correct target but caused "collateral damage" to civilians in the vicinity. These figures seem low to me, and are impossible to verify, as the Pentagon has so far not released a detailed list of NATO errors.

The explanation offered by Western governments goes something like this: "Unlike the Serbs, we never deliberately targeted civilians. When we killed civilians, it was by mistake, not by design. When we made mistakes, we owned up to them."

Unlike many Serbs, I accept that NATO did not deliberately set out to kill or terrorize civilians. But the way we chose to prosecute the war still troubles me. As depicted by NATO briefers, the air campaign was an almost clinical exercise, of "surgical hits" by "precision-guided weaponry." Seen from the ground, it was a much messier affair, in which real people died--people such as Ljiljana Spasic, a 27-year-old Serbian woman in her seventh month of pregnancy who was killed by a NATO cluster bomb on her way to the hospital in Nis. And from the point of view of ordinary Serbs, the distinction between Western behavior and Serbian behavior seems more one of degree than one of kind.

It is true that the United States has made a lot of progress over the years in using technology to limit the impact of warfare on civilians. When the United States and Britain destroyed Dresden in 1945, a third of a million people were killed. A million or so Vietnamese died as the result of the bombing of North Vietnam. Historically, however, the United States has resisted any restrictions on the use of air power, its single greatest technological advantage in waging war. This is the reason Washington refused to ratify the 1977 protocols to the Geneva Convention outlawing the "indiscriminate" use of air power, even though it accepts their spirit.

The point here is not that the Clinton administration had no business going to war over Kosovo or that NATO's supreme commander Gen. Wesley Clark deserves to be put in the dock alongside Milosevic. It is that war is messy and cruel and no side has a monopoly on virtue. In order to drum up public support for going to war, governments simplify the issues and present the conflict as good versus evil. Reality is more complicated. The United States fought what it thought was a just war, with essentially humanitarian motives, but also did things that we have the right and the obligation to subject to very searching examination.

Michael Dobbs, an investigative reporter for The Post, covered the war from Kosovo and Belgrade. He is the author of a recently published biography of Secretary of State Madeleine K. Albright.

CAPTION: An unexploded cluster bomblet found in a field near Pristina, the Kosovo capital.

CAPTION: Obituary notices of Serbs said to have been killed during a Nato attack on the town of Aleksinac in late May.