I don't want to open a can of worms here but :
in any war, the enemy is perceived as non-human : every effort is made to destroy him, and you don't want to think about his mother and children when you are about to fire at a man in anger.
So it is well encouraged in any army to despise the enemy, call him derogatory names (gook, boche, whatever).
It's just easier to believe your enemy is a cockroach.
it is morally condemnable, but effective in the field.
So war is hell, but it is no surprise at all to see pictures like the ones we just saw.
it happens in every war, any army.
It is best to resort to war as a last ditch measure (I don't think THIS war was justified yet, my own opinion), but once you are at war, you can skull**** the enemy if you please, you are here to win.