Agreed on just cause. Also factor belief in one's cultural system. WWII Japanese and Germans, especially the SS, had no problem committing war crimes. The Wehrmacht had more conventional beliefs.
Like America's White Supremacists, the Nazis believed in their racial superiority which gave them the right to murder "mud people". Note which JPP RWers support the mass murder of "libs".
The Japanese, also very racist, were also from a culture that has longer range values than the West. Their belief in their inherent superiority dictated their behavior.