Five-year-old Rahma lies unconscious in the intensive care unit of the 22 May Hospital in Yemen’s southern city of Aden. Her face is covered in burns; bandages swathe multiple head wounds; and her eyes are closed shut under swollen eyelids. When she regains consciousness — or if she does, as doctors could not be sure she will make it — she will discover that she’ll never see her mother again.

Her mother, Naama, was among 10 members of a family, including five women and four children, who were killed in a July 9 airstrike that destroyed the Musaab bin Omar school in the village of Tahrur, north of Aden. The school had been housing families displaced by the conflict between a Saudi-led military coalition and Houthi armed groups and their allies, which took control of the capital Sanaa and large swaths of the country late last year. Ten other relatives, mostly children, were injured in the attack.

Rahma’s aunt Salama, who lost three daughters in the bombardment — one of them a baby of 20 months — kept asking, “Why did they bomb us?” I had no answer for her. In the weeks I spent in Yemen, from north to south, between mid-June and mid-July, I met families every day whose relatives, often children, were killed and injured in such strikes.

Rahma’s aunt Salama, who lost three daughters in the bombardment — one of them a baby of 20 months — kept asking, “Why did they bomb us?” I had no answer for her. Donatella Rovera, Senior Crisis Response Advisor at Amnesty International

The Houthis and their allies are the declared targets of the coalition’s 5-month-old air campaign. In reality, however, it is civilians like little Rahma and her family who all too often pay the price of this war. Hundreds have been killed in such strikes while asleep in their homes, when going about their daily activities, or in the very places where they had sought refuge from the conflict. The United States, meanwhile, has provided the weapons that have made many of these killings possible.

The conflict has worsened an already dire humanitarian situation in the Middle East’s poorest country. Prior to the conflict, more than half of Yemen’s population was in need of some humanitarian assistance. That number has now increased to more than 80 percent, while a coalition-imposed blockade on commercial imports remains in place in much of the country and the ability of international aid agencies to deliver desperately needed supplies continues to be hindered by the conflict. The damage inflicted by a coalition airstrike last week on the port of the northwestern city of Hudaydah, the only point of entry for humanitarian aid to the north of the country, is only the latest example. The situation is poised to deteriorate further: The U.N. World Food Program warned last week of the possibility of famine in Yemen for millions, mostly women and children.

Bombs dropped by the Saudi-led air campaign have all too often landed on civilians, contributing to this humanitarian disaster. In the ruins of the Musaab bin Omar school, the meager possessions of the families who were sheltering there included a few children’s clothes, blankets, and cooking pots. I found no sign of any military activity that could have made the site a military target. But I did see the remains of the weapon used in the attack — a fin from a U.S.-designed MK80 general-purpose bomb, similar to those found at many other locations of coalition strikes.

This was far from the only instance where U.S. weapons killed Yemeni civilians. In the nearby village of Waht, another coalition airstrike killed 11 worshipers in a mosque two days earlier. There, too, bewildered survivors and families of the victims asked why they had been targeted.One of the two bombs dropped on the mosque failed to explode and was still mostly intact when I visited the site. It was a U.S.-manufactured MK82 general-purpose bomb, fitted with a fusing system also of U.S. manufacture. The 500-pound bomb was stamped “explosive bomb” and “tritonal” — the latter a designation indicating the type of explosive it contains.

Mistakes in the identification of targets and in the execution of attacks can and do happen in wars. In such cases, it is incumbent on the responsible parties to promptly take the necessary corrective action to avoid the recurrence of the same mistakes. But there is no sign that this is occurring in Yemen: Five months since the onset of the coalition airstrike campaign, innocent civilians continue to be killed and maimed every day, raising serious concerns about an apparent disregard for civilian life and for fundamental principles of international humanitarian law. Strikes that are carried out in the knowledge that they will cause civilian casualties are disproportionate or indiscriminate and constitute war crimes.

While the United States is not formally part of the Saudi-led coalition, it is assisting the coalition air campaign by providing intelligence and aerial refueling facilities to coalition bomber jets. The sum total of its assistance to the coalition makes the United States partly responsible for civilian casualties resulting from unlawful attacks. Washington has also long been a key supplier of military equipment to Saudi Arabia and other members of the coalition, providing them with the weapons that they are now unleashing in Yemen. Regardless of when the weapons used by coalition forces in Yemen were acquired — whether before or since the start of the air campaign — the countries that supplied the weapons have a responsibility to ensure that they are not used to commit violations of international law.

The poisonous legacy of these U.S.-made weapons will plague Yemen for years to come. In Inshur, a village near the northern city of Saada, I found a field full of U.S.-made BLU-97 cluster submunitions — small bombs the size of a soda can that are contained in cluster bombs. Many lie in the field, still unexploded and posing a high risk for unsuspecting local residents, farmers, and animal herders who may step on them or pick them up, unaware of the danger. In one of the city’s hospitals, I met a 13-year-old boy who stepped on one of the unexploded cluster bombs in Inshur, causing it to explode. It smashed several bones in his foot.

Cluster bombs were banned by an international convention in 2008. But in the 1990s, the United States sold the type of cluster bombs now littering the fields of Inshur to Saudi Arabia. Each of these cluster bombs contains up to 200 small bombs, which are dispersed by the bomb’s explosion over a large area. However, many of these smaller bombs often do not explode on impact, leaving a lethal legacy for years to come.

Coalition airstrikes have been particularly intense in the north of the country, notably in and around Saada, a Houthi stronghold that is home to some 50,000 people. When I visited the city in July, I was shocked by the extent of the destruction: Saada now lies in ruin, with most of the population displaced and private homes, shops, markets, and public buildings reduced to rubble in relentless and often indiscriminate air bombardments. A coalition spokesman said in May that the entire city of Saada was considered a military target, in breach of international humanitarian law, which demands that belligerents distinguish between civilians and military targets at all times.

International law is clearly being violated in Saada and the surrounding villages. A series of coalition strikes on a village in Sabr, near Saada, killed at least 50 civilians, most of them children, and injured nine others in the afternoon of June 3. Half of the village was completely destroyed.

Surviving villagers showed me the piles of rubble which used to be their homes. Ghalib Dhaifallah, a father of four, who lost his 11-year-old son Moaz and 27 other relatives in the attack, told me the boy had been playing with his cousins in the center of the village, at the precise point of impact of one of the airstrikes. “We dug for days looking for the bodies; we recognized some body parts from the clothing only,” he told me.

We dug for days looking for the bodies; we recognized some body parts from the clothing only Dhaifallah, a father of four, who lost his 11-year-old son Moaz and 27 other relatives in an airstrike

While the relentless coalition airstrikes are the biggest killer of civilians so far, civilians also find themselves increasingly trapped in the crossfire between Houthi and anti-Houthi armed groups, with each side supported by some units of the now-divided armed forces. The fighting has intensified since troops from the United Arab Emirates joined the ground operation alongside anti-Houthi fighters, recapturing the southern city of Aden, Yemen’s second-largest city and its main port. As Houthi armed groups have been forced to retreat from Aden and other areas they controlled until recently, they have laid mines that have already claimed dozens of civilian lives.

Many civilians previously displaced by the conflict in the Aden area are now unable to return home, for fear of this lethal legacy from the war.

A negotiated solution to this destructive war remains elusive, as all the parties involved in the conflict have persistently disregarded their obligations under international law. Such impunity has undoubtedly fueled even more crimes. This must change. A United Nations commission of inquiry to investigate alleged war crimes and other violations of the laws of war by all parties in Yemen could be an important deterrent. Whatever the means, the international community must send a strong message to the belligerents that further abuses will not be tolerated and that they will be held accountable — so as to ensure that other children will not suffer the same fate as Rahma.

This opinion piece was first published by Foreign Policy here