Re:
'But it is not a question of what people think. It is a question of the morality of our behavior. "Is it right?", not "Does it make people happy?".'
Certainly it's a matter of morality, but also in terms of international relations it's matter of forming and following international laws.
"You may be implying [not sure, so correct me if I misinterpret] by your statement that I quoted in the subject, that when you are dealing with evil people, then you need not follow any ethical rules. That "all is permitted". If you are, then I think that's a disgusting, anti-Christian, nihilistic (by definition) view."
I think that when you are dealing with evil people, you have to be particularly careful to understand & follow ethical rules.