U.S. forces were responsible for the deaths of at least 105 Iraqi civilians in an airstrike against snipers from the Islamic State in March, according to a report released by Central Command on Thursday.

The airstrike brought considerable international attention back to the Battle of Mosul, which at that point had been raging for five months, drawing widespread condemnation across the world and in the United States. Many observers linked the ‘CIVCAS’ incident to the election of Donald Trump, who has been accused of authorizing a ‘loosening’ of the rules of engagement for commanders on the ground.

Central Command (CENTCOM) pushed back on these allegations, citing the brutal, close-in nature of the fight for Mosul as being further complicated by a densely packed battlefield occupied by ISIS fighters and civilians alike. In an interview with an American commander on the ground, SOFREP reported that the battlefield in Mosul was unlike most other urban battles in modern warfare, with a ‘maze’ of terrain being occupied by ISIS fighters, a result of the ancient ruins modern-day Mosul was constructed on top of. In addition, ISIS has been intentionally packing civilians into buildings which they then use as fighting positions, in a bid to attract the exact kind of CIVCAS incidents as the one in March.

CENTCOM now reports that a single GBU-38 precision-guided munition was used to engage two ISIS snipers who were engaging members of the Iraqi Counter-Terrorism Service, who were positioned in a multi-story structure. The bomb entered the building, detonating on the second story. The resulting collapse of the building killed 101 civilians which were seeking shelter on the bottom floor. Four other civilians were killed in an adjacent building as a result of the explosion.

The executive summary of the investigation indicates that ISIS had adeptly utilized terrain to mask the fact that civilians were still inside the building.

Of note, ISIS had staged a significant number of explosives in the building, which exacerbated the damage caused by the GBU-38.

“The GBU- 38 sparked a secondary detonation of a large amount of explosive material that ISIS had previously emplaced in the structure. The secondary explosion produced a powerful blast and overpressure that triggered a rapid progressive failure of the structure. These events killed the two ISIS snipers, 101 civilians sheltered in the bottom floors of the structure, and four civilians in the neighboring structure to the west”

The report indicates that the building would not have collapsed solely from the use of a GBU-38.