[ALittleLight]

The collateral damage is part of a function that determines if a war is moral. Imagine a scale between zero collateral damage and complete collateral damage. Being able to selectively assassinate our exact enemies on one end and unlimited nuclear or biological war on the other end.

There are possible wars that would only be moral if, and only if, we could ensure some level of collateral damage or less. Perhaps it would be moral to wage war over X, but only if we could guarantee there would be no collateral damage. Conversely, if some country of psychopaths were doing some unspeakably horrible thing Y then it may be moral to stop them even if stopping them would require us to kill them to the last man, woman, and child. We would need very different casus belli to justify a moral war depending, in part, on the amount of collateral damage prosecuting that war would cause.