"No sane person thinks violence is never justified." Plenty of sane people throughout history sacrificed their lives as a testimony to peace, many of them nameless martyrs. If only we had their courage today.
One thing is certain: All countries think their side in a war is justified.
Once weapons are drawn, only bad options remain. Victories on the battlefield are temporary at best.
(I believe we have a moral obligation to foster negotiations to end the war instead of adding more fuel to the fire.)