It seems obvious to me that the proposition is that the plane was misidentified or otherwise somehow accidentally targeted instead of some other target, either

It seems obvious to me that the proposition is that the plane was misidentified or otherwise somehow accidentally targeted instead of some other target, either by human error or by a not-well-enough-supervised automated system - not that the firing of the missile was unintentional. I.e. they are not claiming that somebody accidentally hit the fire button with their elbow, I think.