The large-scale and indiscriminate bombing of Raqqa, Syria by the U.S. military and allied forces last year likely breached international humanitarian law and amounted to war crimes, according to a new report by Amnesty International.

The coalition’s “war of annihilation,” as it was called by Defense Secretary James Mattis, killed hundreds of civilians and injured thousands between June and August 2017, according to Amnesty’s report.

Researchers interviewed more than 100 survivors of airstrikes at 42 locations and found that many civilians had been trapped in the city during the campaign, moving from place to place as houses were bombed.

About 90 percent of the airstrikes were carried out by U.S. forces, and U.S. military officials called the operation “the most precise air campaign in history,” with Army Sergeant Major John Wayne Troxell bragging that “mortars, artillery, rockets, Hellfires, armed drones,” rained down on Raqqa “every minute of every hour.”

“The coalition’s claims that its precision air campaign allowed it to bomb [ISIS] out of Raqqa while causing very few civilian casualties do not stand up to scrutiny,” Amnesty’s senior crisis response adviser, Donatella Rovera, told CNN. “On the ground in Raqqa we witnessed a level of destruction comparable to anything we’ve seen in decades of covering the impact of wars.”