We can be all nice and civilized to them… after we beat them. Kind of like how in World War II we bombed the crap out of Dresden, Hamburg and Tokyo. The régimes in Nazi Germany and Tokyo needed to go away, and the amputations needed to be cauterized. So they were. Then we were nice, very nice actually, with the populations of those countries after the war.
That was, and remains, the only morally correct, strategically effective way to treat hellishly barbarous régimes and terrorist organizations.