HAJJA, Yemen — The airstrike slammed into Al-Sham water-bottling plant at the end of the night shift, killing 13 workers who were minutes away from heading home.
Standing among the strewn bottles, smoldering boxes and pulverized machines a few days after the airstrike here, the owner, Ibrahim al-Razoom, searched in vain for any possible reason that warplanes from a Saudi-led military coalition would have attacked the place.
Nothing in the ruins suggested the factory was used for making bombs, as a coalition spokesman had claimed. And it was far from any military facility that would explain the strike as a tragic mistake: For miles around, there was nothing but desert scrub.
“It never occurred to me that this would be hit,” Mr. Razoom said.
Of the many perils Yemen’s civilians have faced during the last six months of war, with starvation looming and their cities crumbling under heavy weapons, none have been as deadly as the coalition airstrikes. What began as a Saudi-led aerial campaign against the Houthis, the rebel militia movement that forced Yemen’s government from power, has become so broad and vicious that critics accuse the coalition of collectively punishing people living in areas under Houthi control.
Errant coalition strikes have ripped through markets, apartment buildings and refugee camps. Other bombs have fallen so far from any military target — like the one that destroyed Mr. Razoom’s factory — that human rights groups say such airstrikes amount to war crimes. More than a thousand civilians are believed to have died in the strikes, the toll rising steadily with little international notice or outrage.
Rather than turning more Yemenis against the Houthis, though, the strikes are crystallizing anger in parts of the country against Saudi Arabia and its partners, including the United States
. The Obama administration has provided military intelligence and logistical assistance to the coalition, and American weapons have been widely used in the air campaign. Human Rights Watch has found American-manufactured cluster munitions in the fields of Yemeni farmers. Near the site of airstrikes that killed 11 people in a mosque, researchers with Amnesty International saw an unexploded, 1,000-pound American bomb. The United States is finalizing a deal to provide more weapons to Saudi Arabia, including missiles for its F-15 fighter jets.
In parts of northern Yemen, which is populated largely by Shiite Muslims, residents told reporters making a rare visit to the area that the bombing campaign by the Sunni coalition often feels like a sectarian purge. Airstrikes nearest the border with Saudi Arabia have been so intense that people have taken shelter in mountain caves or been forced farther south, often on foot, where they set up flimsy camps on the side of the road.
Neighborhoods in the northern city of Saada have been so heavily bombed that locals joke grimly that the coalition has run out of buildings to hit. The shrinking pool of targets has not stopped the planes that circle daily over Sana, the capital, from bombing the same security buildings over and over again, with a bewildering and terrible frequency.
The Saudi-led coalition has rarely if ever acknowledged killing civilians by mistake, even after the deadliest strikes, like the bombing of a residential compound for workers in Mokha in July that killed at least 63 people. Instead, the coalition blames the Houthis, accusing them of fighting from populated areas.
“Why would we acknowledge something that doesn’t exist?” said Brig. Gen. Ahmed Asiri, the coalition’s spokesman, when asked whether the airstrikes had killed noncombatants. He said it should fall to Yemen’s exiled government or the United Nations to investigate such deaths.
Col. Patrick S. Ryder, a spokesman for United States Central Command, said American officials had asked “the Saudi government to investigate all credible reports of civilian casualties resulting from coalition-led airstrikes, and if confirmed, to address the factors that led to them.”
A tense political standoff erupted into war in March, after the Houthi militias ousted the government of President Abdu Rabbu Mansour Hadi, who fled abroad. Saudi Arabia launched its offensive with the stated goal of returning Mr. Hadi to power, but was motivated by far deeper anxieties, analysts said.
The Saudis, already shaken by the Obama administration’s nuclear deal with their regional rival, Iran
, viewed the Shiite-led Houthis as an Iranian proxy gaining strength just over its border. The Houthis have denied acting on Iran’s orders; Saudi allies, including the United States, said the fears were exaggerated.
More than 4,500 people have been killed in the war. Hundreds have died in street battles between the Houthis and their rivals for control of Yemen’s most important cities, like Taiz and Aden, where residents have accused the Houthis in particular of resorting to brutal force. The ground war and harsh Saudi restrictions on imports have deepened humanitarian suffering in Yemen, causing shortages of fuel, water and medical supplies while inflating prices of food and other goods.
The majority of civilians have been killed by coalition warplanes, often dropping American munitions ranging from 250 to 2,000 pounds. There are no comprehensive tallies of the deaths. But the United Nations Human Rights Commissioner said on Friday that of 1,527 civilians who died between the start of the Saudi offensive and June 30, at least 941 people were killed by airstrikes.
The airstrikes have helped the coalition advance in southern Yemen, where anti-Houthi sentiment is strong. But the mounting civilian toll has raised concerns about the tactics of the coalition of Arab armies fighting alongside the Saudis, and seeking to prove its mettle as a regional counterweight to Iran’s influence. As the coalition has amassed troops and weapons in central Yemen in preparation for a possible ground invasion of Sana, fears have grown that the capital, with its meticulously preserved Old City, will suffer the same fate as other Yemeni treasures destroyed during the conflict.
The United Arab Emirates said its pilots have played a central role in a recent flurry of airstrikes, in apparent retaliation for a Houthi attack Aug. 4 that killed at least 45 Emirati soldiers fighting in Yemen. Since then, Sana has come under its heaviest bombardment of the war. The day after the Emirati soldiers were killed, at least 21 civilians died in airstrikes across the capital, according to relatives of the victims. Bombings in one district killed nine people, in a pattern that characterized many of the attacks.
The coalition jets focused on a university that the Houthis had used as a base, plowing craters in the dirt and bombing a warehouse on the campus that appeared to be full of office furniture. But they also struck a residential area overlooking the university, with at least three separate airstrikes, partially damaging or demolishing six houses.
“They kill innocents and claim to be killing Houthis. They are targeting the whole population,” said Adam Mujahid Abdulla, a 20-year-old survivor of the strikes, who was recovering in a hospital last week, bandages covering burns over 65 percent of his body.
The bomb that struck his house killed seven members of his family. But his friends, visiting in the hospital, were too worried about his condition to tell him that his relatives, including his mother and four siblings, had died.
Across town, another airstrike sliced through a building of shops and apartments, killing seven people. In the rubble, people dug out the remains of Mohib Mohammed, 26, the local barber. “They only found his legs,” said Ayman Mahmoud, who arrived at the neighborhood soon after the airstrike.
The strike’s victims included Tayseer Okba, a 12-year-old girl who that morning had been visiting her 65-year-old grandmother, Amana al-Khowlani.
There is little mystery about the repeated attacks on the northern Saada Province, the birthplace of the Houthi movement. Months ago, the Saudi coalition declared that the entire province was a military zone, drawing an outcry from human rights groups that did little to deter the warplanes.
In border areas that the Houthis have used for attacks into Saudi Arabia, the coalition forces have struck deep into Yemeni territory, bombing hospitals, roads and towns even when no Houthi fighters are present, said Dr. Natalie Roberts, who worked with Doctors Without Borders in one of the few clinics in the province.
Mothers delivered babies in caves where they found shelter. People who were ill waited weeks before traveling to hospitals. “It’s no kind of life,” Dr. Roberts said. “Waiting in a cave to see if you’re going to get bombed.”
A road leading into Saada has been cratered by airstrikes that destroyed at least four bridges and obliterated trucks carrying fuel or livestock. In Saada City, so many houses were bombed in one neighborhood that all the residents simply fled.
Omar Mohammed al-Ghaily, 28, sat in the center of town, near the ruins of his clothing store, destroyed in airstrikes that razed a stretch of government buildings. The strikes killed Seif Ahmed Seif, who owned an umbrella store. Mr. Ghaily kept Mr. Seif’s identity card, maybe to return it one day to his daughter, who lives far away in Taiz. He kept coming to the rubble, he said, because he had “no place to go.”
Saada had suffered mightily over the last decade, when the Houthis fought six wars against Yemen’s central government. But those conflicts paled in comparison to the damage being inflicted by the coalition, Mr. Ghaily said: “this war from the sky.”