WASHINGTON — The American commander in Afghanistan, Gen. John F. Campbell, said on Monday that Afghan forces had requested the airstrike that destroyed a Doctors Without Borders hospital in the city of Kunduz, conceding that the military had incorrectly reported at first that the response was to protect American troops said to be under direct threat.

But General Campbell’s response to criticism of the American airstrike during a brief news conference at the Pentagon did little to clarify the military’s initial claims that the strike had been an accident. Nor did it explain how an AC-130 gunship, a powerful and precise attack aircraft, killed 22 people, including patients and hospital staff members, during more than 30 minutes of firing on the hospital on Saturday morning as Afghan forces fought to retake Kunduz from the Taliban.

Who called in the strike remained an open question, and the military itself appeared uncertain about whether any of the Afghan or American troops involved in the strike knew that they were unleashing a sustained air attack on a hospital.