ONE OF THE deadliest airstrikes in Yemen since a Saudi Arabia-led coalition began bombing the country used munitions supplied by the United States, according to a report by Human Rights Watch.

The March 15 attack targeted a crowded market in the village of Mastaba in northwestern Yemen, killing at least 97 civilians, including 25 children. HRW said it found remnants of a “GBU-31 satellite-guided bomb, which consists of a U.S.-supplied MK-84 2,000-pound bomb mated with a JDAM satellite guidance kit, also U.S.-supplied.” The group said it also reviewed evidence provided by British news channel ITV, which found remnants of an “MK-84 bomb paired with a Paveway laser guidance kit.”

The report provides yet more evidence of U.S. complicity in the indiscriminate killing of civilians in Yemen. The Obama administration has been a key military backer of Saudi Arabia in its yearlong campaign against a rebel movement in Yemen known as the Houthis. In addition to billions of dollars in arms sales, the Pentagon has provided the Saudi-led coalition with logistical and intelligence support. Human Rights Watch said the U.S. role may make it “jointly responsible” for war crimes.

“The U.S. military has deployed dedicated personnel to the Saudi joint planning and operations cell to help coordinate activities,” the group’s report said. “U.S. participation in specific military operations, such as providing advice on targeting decisions and aerial refueling during bombing raids, may make U.S. forces jointly responsible for laws-of-war violations by coalition forces. As a party to the conflict, the U.S. is obligated to investigate allegedly unlawful attacks in which it took part.”

Since the conflict began in March 2015, more than 6,400 people have been killed, nearly half of them civilians, and more than 30,000 injured. According to the United Nations, airstrikes have been responsible for the majority of civilians deaths. The Saudi-led coalition has been accused of numerous violations, including the targeting of civilians and civilian infrastructure, such as hospitals, schools, and factories.

“The U.S. and others should pull the plug on arms to the Saudis or further share responsibility for civilian lives lost,” stated Priyanka Motaparthy, emergencies researcher at HRW.

The bombing of the market in Mastaba last month was perhaps the deadliest attack of the entire war so far. Journalist Mohammed Ali Kalfood visited the site after it was bombed and interviewed a survivor who provided a heart-wrenching account to The Intercept: