The top American air commander in the Middle East voiced frustration in an interview last week over the murderously incompetent Saudi-led air campaign in Yemen. Though welcome, his sentiment was far too mild. It should have been more like horror — and shame over American complicity in what a new United Nations report views as criminal carnage.

Saudi Arabia and its Sunni allies intervened in Yemen more than three years ago to rout Iran-backed Shiite rebels who had driven the internationally recognized government out of the capital and into Saudi exile. As the conflict has dragged on, the rebels have also been accused of atrocities, but the United Nations body and human rights groups say it is the Saudi-led air war that has done the most to turn an already impoverished country into a humanitarian nightmare and an indiscriminate killing field.

Again and again, Saudi-led airstrikes have struck civilian targets, slaughtering innumerable innocents. Last Friday, the United Nations said the coalition killed at least 22 children and four women as they fled a battle zone. Two weeks earlier, on Aug. 9, a coalition air assault struck a school bus, killing dozens of children. Countless more civilians have been killed by bombs at markets, weddings, funerals — more than 6, 500 by the official count, but certainly many, many more. Millions more civilians are suffering from shortages of food and medical care.