Religious Zionist rabbis mistakenly encourage youths to join the army to fulfill melhemet mitzvah, the commandment of war. The rabbis point to the Arabs’ bellicose policies and shelling of Sderot as proof that Israel wages a defensive war in which participation is obligatory. They fail to differentiate between preconditions and implementation.
There clearly exist sufficient preconditions for obligatory war: not only do Edomites threaten Jews, but they demand Jewish land. Halacha unconditionally requires us to fight, even if the enemy demands only straw and hay, and under no circumstances are we allowed to relinquish Eretz Yisrael. On that, we have the precedent of Judge Yiphtah, who led Hebrews into battle when our enemies offered a land-for-peace deal. In obligatory wars, Jewish lives are subordinated to Jewish values.
But the State of Israel is not fighting an obligatory war. In such a war, everyone goes out, including newlywed husbands and—according to some opinions—wives, young and old, laypersons and Torah scholars. When Rabbi Akiva authorized obligatory war against the Romans who sought to extinguish Jewishness, he sent all his students to fight in Bar Kochba’s ranks. That is rabbinical responsibility: you authorize it, you fight in it.
The Torah prescribes a code of obligatory war: no enemy should be left alive, women and babies included. They attacked the commandments, they attempted to conquer the cities of our God, and they rebelled against His people; the only fitting punishment is death. If we left babies alive, they would grow up and avenge their slain parents; that we cannot afford.
The commandment to accept their surrender only applies to expansionary, rather than obligatory wars: if they gave up when we besieged their town, and accepted on themselves tribute and servitude, we allow them to stay in our land. But once they took up arms, there was no mercy. Actually, there was: what the rabbis called, “the mercy of fools,” mercy to the merciless. Likewise, the commandment to spare their women only applies in expansionary wars, those we started outside Eretz Yisrael.
God cares about Jews. When he sends us to fight over trivial issues, be it hay or desert, he protects us. Not only through his direct involvement, but also by releasing us of constraints. When he sends us to fight, surely he does not endanger us beyond necessity. God does not tie our hands with politically correct rules of engagement, nor would he make us leave our enemies alive to resume fighting as soon as the shock is over. Hebrews defeated Amalek in the first encounter, but were still told to extinguish him.
When the rabbis tell their students about obligatory war, the rabbis also have an obligation: to tell them how to fight it.