our pentagon correspondent jim miklazewski is working that story for us tonight and has fresh details. >> reporter: the evidence was undeniable, the hospital run by doctors without borders in kunduz was in flames, devastated by a usair strike, killing at least 24 hospital staff and patients. the air strike was carried out by an ac-130 gun ship. nbc news learned that cockpit recordings reveal that the crew actually questioned whether the air strike was legal. a defense official said today it may, in fact, amount to a war crime. for three days the u.s. military failed to acknowledge innocent civilians were killed. >> an air strike was called to eliminate the taliban threat and several civilians were accidentally struck. >> reporter: four full days after the strike, the u.s. commander general john campbell admitted the worst. >> the hospital was mistakenly struck. we would never intentionally target a protected medical facility. >> reporter: a preliminary investigation indicates the u.s. military forces apparently failed to follow strict rules of engagement in identifying the target. def

jim miklazewski live for us from the pentagon. thank you for that. >>> joining me is senior fellow for the center of american progress. harden, 22 people killed in the air strike. the u.s. saying it was afghan officials who had asked for the air strike. what should have happened in a case like this where there are afghan forces on the ground supported by u.s. air support. >> what is deeply troubling about the nature of this tragedy is the afghans on the ground called up through the ac-130 gun ship with request for close air support. on that ship you are going to have someone with special operations background who can interpret what they are hearing and guide the request. the fact this broke down in such a significant way is not only a tragedy, but it's going to send people back to the book to have a real look at the protocol about how this sort of thing happens. the second piece, it may raise certain questions about the nature of the overwatch u.s. military is providing from the air in terms of close air support. we don't have the