Why adhere to it if your opponent is not going to? I am not saying we should slaughter innocents, and I do not think our troops would do it.
Appling rules to war seems a tad silly to me, the allies in WW2 bombed cities out of existence and the civilian death toll be damned. We did it because we where convinced it would shorten the war. in turn saving lives over all( most importantly the lives of our troops)
Yet we moralized over the SS burning French resistance in a church?
So if we can brake the rules and no one really gets hurt, and it brings in the guy we need to find sadam, or WMD or even help cut resistance then go for it.