Why is war more accepted by society than a school shooting?

Actually school shootings don't occur for no reason, most are a result of bullying. Unfortunately retaliating in such a way against unarmed people is not acceptable behavior. War is usually the result of one country over stepping the boundaries and attacking innocent people in another country, which results in retaliation, or is imposed to settle disputes. Nobody approves of war, but sometimes you have to do it in order to make other countries understand they can't walk all over us. Sometimes violence is the only way to make others comprehend how damaging their behaviors are, in both cases the reasoning behind it is the same, you can't reason with unreasonable people, whose only function in life is to har and terrorize others. In situations like that it is kill or be killed. If your going to bully someone to the point that they lose their will to live, you may as well just pull a trigger and kill them .