[BeHoldAPaleHorse]

Where ever the enemy draws the line.

That is a non-answer.

So what conduct would be permissible for our troops? Give me a simple answer.

[F.J. Mitchell]

My answer is: Whether in a butt kicking contest in a bar, or in a war against people who obey no rules, and they started the fracas, you just keep hurting them much worse, every time they hurt you, until they can't handle the pain anymore.
What's so difficult to understand about that?