Okay, I skimmed your story. Touching, but a heart-wrenching story isn't going to change my mind. At war, people die. You want justification? The father died because he was killing people, and if whoever shot him hadn't, he might have been killed too. In fact, he probably was killed. Violent people die unnatural deaths.
Can violence and murder be justified? Yes. Can war be justified? Yes. Why am I still discussing this? Why am I letting you goad me with each post?