Dear Yoni, We named you Jonah, the dove of peace, but, today, joining the Israeli army made you an instrument of war. Of course, that’s only half the story.The IDF fights for justice, dignity, and most important, self-defense. The cliché remains true: Israel would disappear if young heroes like you stopped defending us – and peace will appear when our neighbors stop attacking us.Once, the Colt .45 revolver was the Wild West’s “Peacemaker”; today, you and your buddies are the Middle East’s peacemakers – protecting the civilized world against Islamist terrorism.True, ambiguities lurk beyond those absolutes. When serving in the Israeli army – or any democratic army today – you must focus on the purity of your motives to defend your home and our values, relying on sweeping statements to survive scorching days and freezing nights; stupid tasks and idiotic commanders; physical pain when you can’t run or hike or train any longer, and terror when every instinct says “run from danger” and you run toward it.Yet, modern warfare and especially Israel’s current situation is often messy. You will face terrible dilemmas demanding instant action – then be judged by armchair critics.Try keeping your moral compass in this amoral world.The IDF code commands soldiers “to give their all” yet “maintain their humanity even during combat.” You must act robotically while remaining a thinking, feeling, moral being, a Jew fighting for our lives, our homes, our ideals. IF OUR ancestors were fiddlers on the roof, perched precariously in their helplessness, you soldiers must proceed cautiously because of your immense power. A flak-jacketed and armed fiddler on the roof, you will balance contradictions. You sacrifice your freedom to defend our freedoms; you risk your life to defend ours. You must meld into your unit while preserving your individuality.You will have to do brutal things while preserving not just your body but your soul.Watching you and your friends enlist is uplifting yet heartbreaking. One by one, you shave your heads, go to train, and return buffer, tougher, matured by the experience – but still the exuberant high-schoolers who buzzed themselves in and out of our house freely. Even while being trained to kill, you retain the capacity to laugh – an amazing feat.IDF training is grueling. It’s boring and arbitrary, not just exhausting and stressful. And when you wear that uniform, you don’t become superheroes but do become targets for terrorists.We delight in all of you, proud of the Hartman community which produces such idealistic soldiers serving in impressive units. But we wonder which of them, which of us, will lose that unlucky lottery, suffering the Palestinian Wheel of Meted-out Misfortune that destroys lives.Chief of Staff Gadi Eisenkot insists: “An 18-year-old man serving in the army is not ‘everyone’s child.’ He is a fighter....” Eisenkot’s job is to treat you like the man you need to become. And our job is to love you like the kid you still are. Yet, we trust Eisenkot to remember that you’re all “our kids.” And you trust us to welcome the man you’re becoming.Last Shabbat’s Torah reading described Moses’s reluctance as a leader – like most kids commanded to sacrifice their freedom for national service (although you and your gang are exceptionally gracious about this). God responds by detailing Moses’ roots. Rabbi Stewart Weiss, a fellow immigrant and Jerusalem Post columnist, explains the communal message: “You belong to the nation, and the nation belongs to you.”Similarly, the dove, your namesake, is defenseless, except by flying together in flocks. By uniting you and your fellow soldiers will make forge yourselves into a unit. Still, I plead, stay safe. Winston Churchill said “there’s nothing more exhilarating than to be shot at without result.” For parents, more exhilarating is for their children never to being shot at at all.I know you joke that when you come home, I suggest articles and Mom offers hugs (and food). Just as she frequently learns with you, intense feelings bubble beneath my intellectual façade. When you – and your siblings – rejoice, my heart leaps; when you guys suffer, my heart plummets into the pit of my stomach.I worry. Rabbi Weiss lost his son Ari in 2002, defending us against that evil wave of Palestinian terrorism rejecting negotiations that distanced many of our friends from Israel – as if being attacked was our fault – yet drew us as a family closer to Israel.At Ari’s funeral, Ra’anana Mayor Ze’ev Bielski honored the Weiss family for choosing Israel. “I, who was born here, never had the opportunity to make that choice,” Bielski said.Rabbi Weiss ended his eulogy by asking the mourners to go home and sing “Am Yisrael Chai” – the Jewish people live. You sing that song daily, albeit often silently, tunelessly.Remember, you’re not just defending our family and friends. You’re serving – and singing Am Yisrael Chai – for Ari Weiss and 30,000 Israelis murdered by war and terrorism. You’re serving – and singing – for six million Jews massacred because we didn’t have strong, altruistic soldiers like you. And you’re serving – and singing – for millions more who for millennia dreamed of these amazing realities we take for granted.Yes, it’s a costly burden for you – and an emotional drain on us. But what a gift you’re giving to the Jewish people, and to democratic ideals worldwide. Am Yisrael Chai.Stay safe. We love you, are proud of you – and thank you.The writer is professor of history at McGill University and the author of 11 books.Follow on Twitter @GilTroy.