■

Sometimes, the wars occur not on benefits but on justice, such as resistance against invasion. In that situation, war is vital for protecting something important from someone who wants to deprive it. But it is notable that army don’t protect people. Only people can protect them-self, as history tell us. (See Okinawa, what was the purpose of that fight. Why they died.)
And, it is also important that sometimes attack is induced by the people who want to strengthen their power, to obtain further benefit, to oppress people. 9.11 is doubtfully.