Following two days of intensive bombing in Karbala, Iraq, in 2003, Jabar Raheem and her six-year-old daughter, Duaa, emerged from their house to get water. Along the way, Duaa found a black plastic object shaped like a C-cell battery and attached to a white ribbon. She took it home to share with her sisters, three-year-old Duha and eight-year-old Saja. Sitting on the kitchen floor with the device, Duaa twisted a screw. It exploded, cutting her in half, killing Duha, and severely injuring Saja. “We thought we were safe because the bombs had stopped,” their grief-stricken mother said. “My daughters were stolen from me.”

The weapon responsible for that gruesome tragedy was a U.S. cluster bomb. According to a 2007 report from Handicap International, 98 percent of the casualties from cluster munitions are civilians, of whom 27 percent are children.

Last August, an international Convention on Cluster Munitions went into effect, two years after its adoption in Oslo, Norway, by 108 nations. So far, fifty-two signers have ratified the convention. It prohibits the production, stockpiling, transfer, and use of these weapons, and it provides assistance for those, like Saja, who have been injured by them. Unfortunately, the United States—along with Russia, China, and Israel—has neither signed nor ratified the agreement.

Cluster bombs have been used in conflicts in thirty-five countries and regions, including Laos, Iraq, Afghanistan, Lebanon, Chechnya, and the former Yugoslavia. Early versions of the weapons were employed by the Soviets and the Germans in World War II, and the United States has used them in almost every conflict since Vietnam. In 2003 in Iraq, our armed forces used over ten thousand cluster bombs.

Technically known as Cluster Bomb Units, or CBUs, these weapons are dropped from planes or launched from land and sea by artillery, missiles, and rockets. Inexpensive to produce, cluster bombs differ from munitions designed to strike a single point. Each bomb contains up to 650 bomblets or submunitions that can be dispersed over a target area (or “footprint”) as large as two football fields. The bomblets are sometimes attached to small parachutes, so they can float down over targets. They come in various shapes and sizes, are sometimes brightly painted and can resemble batteries, tennis balls, soda cans, or hockey pucks. Each submunition contains shrapnel (steel pellets or ball bearings) that is released when detonated in midair or on impact. The weapons are used to wound or to kill enemy soldiers, especially in mass formations, but the shrapnel can also penetrate and incapacitate tanks, armored personnel carriers, and grounded aircraft.

Supporters of the ban, like Virgil Wiebe (an international law scholar and cofounder of the Cluster Munitions Coalition, a network of groups campaigning against cluster munitions), argue that the weapons are immoral because they inevitably cause harm to civilians. A similar criticism was made on the eve of the U.S. invasion of Iraq in 2003 by Bishop Wilton D. Gregory, who at the time was president of the U.S. Conference of Catholic Bishops. “Any implied or express threats to defend against Iraq’s weapons of mass destruction by using our own weapons of mass destruction,” including “antipersonnel land mines, cluster bombs, and other weapons that cannot distinguish between soldiers and civilians, or between times of war and times of peace,” he wrote, would be “clearly unjustified.” A 2008 statement of the World Council of Churches describes the CBU as “an indiscriminate instrument that confounds the intentions of its users and brings terrible consequences to its victims.” These criticisms hinge on the just-war jus in bello principle of discrimination—or noncombatant immunity—that prohibits intentionally targeting and harming civilians.

Defenders of CBUs argue the munitions can be used discriminately. In a 2001 Air Force Law Review article, Maj. Thomas J. Herthel argued that cluster bombs “are not indiscriminate by their very nature.” Herthel reminds us that it is possible to use any weapon illegitimately. A surgeon’s scalpel could be used for murder rather than to save a life; everything depends on how and why the scalpel is used. Herthel claims cluster bombs can be used in ways that discriminate between combatants and noncombatants, particularly if they are used to target troop columns, anti-aircraft units, and tank formations in an open field. The just-war principle of discrimination allows room for unintended civilian casualties (“collateral damage”). Further, the Catechism of the Catholic Church (2269) states that “unintentional killing is not morally imputable.”

But the question remains whether the use of cluster munitions in places like Iraq and Afghanistan, which has resulted in significant civilian casualties, met just-war criteria, and whether their use was part of a strategy designed to dispirit and thus defeat the enemy. Catholic ethicist Barbara Hilkert Andolsen has argued that the U.S. military carefully selects legitimate bombing targets when deploying cluster munitions to minimize collateral civilian casualties. I tend to agree with her that U.S. military units in Afghanistan and Iraq have not intentionally used cluster munitions to target noncombatants. Still, the fact that cluster bombs continue to kill and injure people long after hostilities have officially ceased raises serious moral and ethical questions.

The injuries sustained from these weapons often last a lifetime. Furthermore, many of the bomblets do not explode until years after they were deployed. Submunitions may fail to detonate if they land on soft surfaces like sand, mud, weeds, water, or snow. And there are inevitable mechanical failures. In Kosovo and in Afghanistan, for example, dud rates have ranged from 5 to 30 percent, depending on the type of bomb and other conditions. In Kosovo alone, tens of thousands of bomblets remained unexploded after the war, and they may pose a risk for decades to come. In Laos, the United States dropped 80 million cluster bomblets. With at least 10 percent of them failing to detonate on impact, millions were left unexploded and scattered across the country. Although the bombing there stopped in 1973, two to three Laotian civilians still die each month from explosions. Those civilian casualties are in a very real sense “predictable”: the same scenario repeats itself every time cluster munitions are used.

But if this is the case, the manufacture and deployment of CBUs must be considered a pattern of “callous disregard for human life.” In certain circumstances, one can be accountable for the unintended side effects of one’s actions. If an intoxicated driver, for example, injures or kills someone, that driver is morally culpable and legally blameworthy. The injuries or death were not intended, but neither were they totally accidental.

Thus Herthel’s claim that cluster bombs are not designed to cause civilian casualties warrants further scrutiny. Clearly, making and decorating these weapons is intentional. The question is: Are they designed in such a way as to be easily mistaken by civilians, and especially children, for soda cans, tennis balls, or batteries? While an individual soldier or military unit might not be guilty of acting indiscriminately in deploying cluster munitions, there is room to wonder whether a nation deploying them—and doing nothing to make sure they don’t resemble toys or soda cans—has some degree of moral culpability. The fact that the United States initially used the same yellow color for both humanitarian food parcels and cluster bombs in Afghanistan—leading some civilians to mistake the bombs for food—but later changed the color of the parcels and broadcast warnings to the population indicates both that there is a real problem and that it can be addressed.

Also, given the dud rates, why haven’t technological safeguards been more vigorously pursued? Those who design and deploy cluster munitions ought to be doing everything possible to minimize predictable noncombatant casualties. Yet, given the fact that cluster bombs are meant to disperse bomblets over such wide areas, and that a 1-percent dud rate is the optimum, unacceptable numbers of unexploded weapons are bound to plague those areas.

Because 98 percent of the casualties caused by cluster bombs are noncombatants, and because unexploded ordnance impedes farming and the resettling of displaced people, it’s hard to see how the use of CBUs passes the proportionality test, which requires the intended good effect to outweigh the unintended but foreseeable bad effects. In wars such as the one in Afghanistan, where it is crucial to win the support of the civilian population, causing such high rates of noncombatant casualties is sure to provoke resentment and lead to future retaliation.

An analysis of cluster bombs and their use in terms of the just-war principles of discrimination and proportionality leads one to conclude that their continued use by nations like the United States—which refuse to sign and ratify the international convention—is indefensible. Let us hope that the moral stigma most of the world now puts on these weapons, in addition to landmines and poison gas, will deter even the nonsigners from using them.