I was recently rewatching the original Stargate movie. MASSIVE SPOILER FOLLOWS
In it, Ra is waited on by an entourage of child attendants, who, when he is threatened, are trained to instantly act as a human shield.
Of course, when they do that, our guys stop their attack. They're not going to shoot a bunch of children.
However, all's well that ends well. Ra is finally defeated, and Earth is saved, when O'Neil nukes his ship and kills him.
And, in the process, presumably kills those same children (and the cat).
This made me think of Hiroshima. It has been argued that the bombing was justified, because of the many more lives it potentially saved.
However, would those who ordered or carried out the attacks have considered it an acceptable loss of life if they had had to individually execute all of those tens of thousands of civilian men, women and children? Or even mow a crowd of them down with machine guns?
It seems to me that, if war is considered to be ethical at all, the more hands on the better. If you are fighting hand to hand with an enemy who you can see (and who also has a fair chance of killing you) you know what you're doing, and you're putting your life on the line for your cause, whatever it is.
Throwing death from a distance at unseen enemies dehumanises them - and hardens you.