Few traditional sources discuss the ethics of fighting noncombatants, but some Jewish laws of war do display a moral genesis.
Deuteronomy 20 permits wars of aggression, but the talmudic rabbis made it difficult to declare one.
When lives are at stake, Judaism permits--and probably requires--fighting.
Judaism distinguishes between commanded wars and permitted wars.
Combat and Conflict in Jewish Tradition. Jewish Views on War and Peace. Jewish Ideas and Beliefs.
An incomplete lifecycle process or an unsuitable attitude may exempt you from service.
Jewish tradition never embraced complete pacifism, though minimizing violence has always been a priority.
War & Peace
In Judaism, peace is not merely the opposite of war, but denotes an ideal state of affairs.