First is a general allowance for war.
(Proverbs 24:6 KJV) For by wise counsel thou shalt make thy war: and in multitude of counsellors there is safety.It seems obvious to me that if you need wise counsel in order to make war and there is no statement condemning war in general, it is not always forbidden.
One of the principles in just war deals with limiting your response and not giving in to the urge to rape, pillage and burn.
(Proverbs 24:17-18 KJV) Rejoice not when thine enemy falleth, and let not thine heart be glad when he stumbleth: Lest the LORD see it, and it displease him, and he turn away his wrath from him.This is just a short moment. Maybe when I retire I will get back to more detail. The point is that there is no requirement for being a pacifist. There is a requirement to limit the carnage and keep you attitude in check.
homo unius libri