Agreed. It is long been part of Jewish law that there are different types of war, and difference allowances for them. One can't fight a war just because one wants something another has, one may fight a war if there is a likelihood of being attacked otherwise (not required to fight), one must of course defend against an attack, and in the instance of one whose soul is fixed on the destruction of Israel, they must be fought. Obviously, the IDF follows modern secular law, but the point made was that the terrorists fall within that last category, and it's not just okay to destroy the, Israel must do so to survive.