In the tenth chapter of Bhagwat Gita, you find that the supreme form of God reveals itself in a frightful way, as a force that destroys everything, as a potential that triggers a circuit or path.

And it is interesting that this revelation of the divine in its supreme form goes in correspondence with a warrior, Arjuna, who during the combat encounters family and friends in the enemy army that he has to fight, and the divinity encourages him by saying: 'All those you see over there are already dead. Since they are born they are all transported by a destructive force, since none of them is the author of the transcendence I am. So advance towards the enemy without fear. Become my man and fight with no concerns or fears.'

I believe this is the highest and most sacred justification of war that one can find in the traditional world.