The international aid agency whose hospital in Kunduz, Afghanistan was bombed over the weekend is refusing to let the U.S. military forgo responsibility for the attack even as the Pentagon changed its story again on Monday and tried to pass blame to Afghan forces.

“The reality is the U.S. dropped those bombs. The U.S. hit a huge hospital full of wounded patients and MSF staff. The U.S. military remains responsible for the targets it hits, even though it is part of a coalition. There can be no justification for this horrible attack. With such constant discrepancies in the U.S. and Afghan accounts of what happened, the need for a full transparent independent investigation is ever more critical.” —Christopher Stokes, MSFThe U.S. military admitted on Monday that its initial account of its bombing of a hospital run by Doctors Without Border/Médecins Sans Frontières (MSF) was false.

General John Campbell, who commands the 9,800 U.S. troops in Afghanistan and holds ultimate responsibility for Saturday’s bombing, said that—contrary to the military’s initial claims—the deadly attack was not in response to fire from the  facility, but was “called in” by Afghan commanders.

Campbell, however, provided few details, stating that the military will release a “preliminary report” in a few days. However, MSF has repeatedly demanded a transparent investigation to be conducted by an independent body—not the U.S. military—into the attack, which the group charges was a war crime.

What’s more, Campbell declined to apologize for the attack that killed 22 people, including 12 staff members and 10 patients—3 of them children. Thirty-seven others were wounded in the bombing.

Reportedly, MSF had given repeated notification to the U.S. military of its coordinates, including five days before the attack, and called the U.S. during the bombing urging them to stop.

In addition, Campbell appeared to pass off responsibility for the killings, declaring: “Unfortunately, the Taliban decided to remain in the city and fight from within, knowingly putting civilians at significant risk of harm.”

MSF, which has strongly criticized the U.S., once again blasted the military for continuing to evade accountability.

“Today the U.S. government has admitted that it was their airstrike that hit our hospital in Kunduz and killed 22 patients and MSF staff,” said Christopher Stokes, general director for MSF, in a press statement.

“Their description of the attack keeps changing—from collateral damage, to a tragic incident, to now attempting to pass responsibility to the Afghanistan government,” the organization added. Previously, U.S. Army Colonal Brian Tribus, spokesperson for U.S. forces in Afghanistan, said that the airstrike was conducted “against individuals threatening the force. The strike may have resulted in collateral damage to a nearby facility.”