War on hostile intruders is an extension of civil order as outlined in the Christian scripture of Romans, chapter 13.
This is no endorsement of military adventurism of course, but again this doesn’t apply in this case.
3 For rulers are not a terror to good works, but to the evil. Wilt thou then not be afraid of the power? do that which is good, and thou shalt have praise of the same:
4 For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil.