I think it’s mostly been covered already–it is unlikely, or at least not well established, that Obama or any other recent President ordered any type of aerial strike deliberately targeting noncombatants. Under international treaties we have signed, such deliberate targeting would constitute a war crime, but I’m not personally familiar with any such orders or such cases, with the big caveat that there have been many aerial strikes in the Middle East ordered directly by recent Presidents, and I’m not even familiar with an appreciable percentage of them and their specifics.
I do like to point out because this is a point often missed in such discussions–our treaty obligations do not require us to “avoid all civilian deaths” or to “never harm the hair on a civilian’s head.” International law in terms of treaties we have signed, basically say we cannot deliberate make civilians the target of an attack. This gives the military wide latitude. For example let’s say there is an Iraqi Children’s Hospital right next to a major Iraqi military communications facility, and this is right before the invasion of Iraq. That communications facility is a valid target of war, so we launch a cruise missile at it. Sadly the cruise missile is not as accurate as we would hope and slams into the hospital, killing hundreds of children.
This is a terrible thing, a tragedy. Compounded by the fact that most of us feel the invasion of Iraq was unnecessary, many view that invasion as illegal (that issue is quite complicated and not worth litigating right now), however this hypothetical strike would not be illegal. The dead civilians are “collateral damage” unintended casualties of a “miss” on a valid target.
I also think we have a broader moral obligation to take reasonable effort to minimize incidents like I just exposed, and I actually think there is evidence we have. We increasingly use smaller explosives on vehicles that can more precisely target them, specifically to reduce collateral damage. Drones actually help with this, because they can more safely get much closer to a target than an airplane which we also risk losing a pilot flying too low, and drones generally carry smaller missiles than full size bombers, smaller missiles, closer range, generally means higher accuracy and less collateral damage.
Does that mean drones raise no moral questions at all and should be considered hunky dory? Of course not, but it does mean that it is unlikely most U.S. drone strikes constitute war crimes. Remember, we wrote the laws on war crimes more or less, we were instrumental in the text of every one of these treaties we signed, and also in the wording of domestic laws that implemented them. Do you really think we would have promoted treaties that so hamstrung our President that he couldn’t order attacks on our enemies? Just not reality.