The mindless mantra "We're better than that" doesn't apply in a hot war; that is, unless your objective is to get your arse kicked ... kicked hard! Cheers!
We are certainly not “better than that”.
We think what we think, and those thoughts in themselves are sins. Thinking about shooting that creature is already a sin, and a fit point to bring up in confession. I have no aspiration to become sinless.
The point of it all is utilitarian. It is a matter of habitual discipline, directed, in war, to specific political goals. Victory matters more than anything, more than personal passion, more than personal survival. One captured, non-dangerous terrorist more or less matters not at all, he is an irrelevant cipher, a number in a prison camp. If one makes the creature a martyr he is no longer a cipher, and that detracts from your goal of victory.
We are not machines. Under the strain of fatigue, fear and tragedy we can let passion direct us. But that submission to passion is still a failure.