Take it to the extreme, and you have nazi atrocities and 'just following orders'.
The former is about operational readiness. If your army is unable to shoot at the enemy for whatever reason, you don't have a functional army. Wars are lost because of this (which leads to political concessions and loss of resources/influence/etc), and it's an important topic to consider when your goal is to maintain a standing army like the US.
The latter is, well, morality.
Of course, these two topics clash. How far do you go to ensure an obedient and effective army, while allowing leeway to refuse orders that are immoral?
Same army will be far more motivated to fight to defend the homeland than to kill a poor sod in a faraway land for unclear reason. So it's not a static quality.
And every time there is a fuckup from the higher ups it affects morale.
Recent headlines about the US killing 30 farmers make it easy to confuse the context. I'm sure the operator(s) involved with that operation are traumatized. But that's not really the discussion here.
As per the article
> The rates of drone pilot burn out were in fact higher than that of traditional pilots.
> Given that the target often posed no direct threat to the sniper, there was a moral dissonance about taking the life of someone who is no direct threat. This has obvious parallels to drone pilots.
> Couple this with the familiarity that the drone pilot might have developed through long-term surveillance, and the target becomes an informationally rich human, rather than simply a blip on a screen.
> Posing a threat to someone is often seen as a moral requirement in order for a solider to use lethal force against a target. However, the drone pilot is acting remotely, and they lose this sense of moral justification for their action.
> One important thing to recognise is that such moral injury is not dependent on the pilot actually committing something morally prohibited.
> For instance, if a soldier must use lethal force to protect an innocent family against an enemy soldier threatening the family's lives, the soldier's actions are typically deemed justified.
> However, given the features of drones, this moral justification might not be properly felt by its pilot.