Yes, destroying civilian targets with no valid military usage is considered a war crime.
Destroying a civilian building being used as a military facility, on the other hand, is not a war crime, except if there was no valid military purpose to the strike or the strike was not proportional to the military value that might be gained (e.g. it would never be acceptable post-Geneva to kill 1000 civilians just to destroy an enemy soldier). That was one of the justifications the Germans used to sink Lusitania (which despite American and British protestations, it appears the Germans had actually been right in retrospect).
If you go into a field and there's a bunch of armed VC villagers who start shooting back at your then an air strike is militarily justified, until the defense ceases.
If you go into a field and there's a bunch of women and children (unarmed!, and I hate that I have to mention that...) then there is no valid military purpose to an air strike.
Now, from just the air if you have good intelligence that there is a grouping of enemy soldiers at a concentration point then even under Geneva that might be all the valid military purpose you need to approve dropping bombs at that location, even at risk of collateral damage.
A war crime would be a military action taken out of proportion to the valid military purpose that might justify it. E.g. if it was known that there were lots of civilians and just a few fighters at that location. Or if you shot a soldier in the act of surrendering (note how rarely U.S. soldiers are afforded even the opportunity to surrender in the few times Taliban managed to encircle a U.S. squad).
I, too, wish that we lived in that wonderful world where civilians are not used as human shields and that all intel is perfect (God knows NSA is trying!) but that's not the world we live in. The world we live in has both Geneva Conventions and the precedent of Nuremburg and does not simply define "war crime" as "things that happen which we don't like".
If you try to redefine "war crime" we'd simply have to come up with yet another definition to mean what it's supposed to mean for things like war crimes tribunals.
You were asked, if you accept "oops" as a valid excuse, is it possible to successfully prosecute any war crime? Can you think of any examples of war crimes where "oops" could not be used as a defense?
"If you go into a field and there's a bunch of women and children (unarmed!, and I hate that I have to mention that...) then there is no valid military purpose to an air strike."
If you accept "oops" as an excuse, then guess what? That air strike was an "oops".
Another very obvious example was the My Lai massacre itself. It's really hard to find a valid military purpose for either carrying out the order to bayonet a child, or giving the order to kill a child.
But the fog of war is not as hazy on the ground. During WWII (which was admittedly a total war) you could drop all the bombs you wanted at a tank factory and still manage to hit the school a kilometer away. That wouldn't have made dropping the bombs a war crime by any stretch of the imagination though; the raid itself had a valid military purpose.
Yes, the perpetrators got off with essentially no punishment whatsoever, the U.S. tried to cover it up, one of the very few heroes was actually punished even further for allowing the story to come out.
All deplorable, and a very deep stain to have associated with the U.S. for all time.
But what does that have to do with the definition of a war crime?
How the fuck do you think this is about the definition of war crimes?
This is about what we consider valid defenses, and our ability to prosecute war crimes. Do you not understand how our absolute failure to prosecute the My Lai Massacre might be relevant to how we prosecute war crimes?
Christ, it is almost as though you have absolutely no interest in understanding what people are saying to you.
