Thomson Reuters
Smoke and flame rise after what fighters of the Syria Democratic Forces (SDF) said were U.S.-led air strikes on the mills of Manbij where Islamic State militants are positioned, in Aleppo Governorate
Garver said a credibility assessment had been completed and the formal investigation had been initiated.
Activists inside Syria claim that the coalition airstrikes left at least 73 civilians dead, a majority of them women and children.
"This is likely the worst reported civilian toll of any coalition attack since the bombing campaign against Isis began nearly two years ago," Chris Wood, the director of UK-based monitoring group AirWars, told The Guardian last week.
"Since the siege began it's our view that at least 190 civilians have been killed by coalition airstrikes, mostly US," Wood added, referring to the regime's siege on Syria's largest city, Aleppo. "We are concerned that the US-led alliance appears to have relaxed some of their rules concerning civilian casualties."
Army Col Christopher Garver, the chief spokesman for the US-led anti-ISIS coalition, implied that the non-combatant casualties may have been the result of ISIS using civilians as human shields.
"We have seen Da'esh using more civilians as human shields in the Manbij area," Garver told The Guardian, using an alternate name for ISIS.
"We've seen them during the fight pushing civilians toward the lines of the SDF [Syrian Democratic Forces] to try to draw fire. While the investigative process will provide details on this particular incident, and we don't know what happened, I won't be surprised if this is somehow a factor."