Well, honestly, a draft will be the least of your worries if Russa backs up Iran if we do attack. But to answer your question, yes there would be a draft imho. The troops currently in right now, most have served already 3 or more combat tours in Iraq or Afghanistan. Do your research on this - so yes there would be a draft, but hopefully cooler heads will prevail as if this war happens, no-one wins. All our lives will change for the worse for the rest of our lives as I have no doubt this will rapidly escalate to the unimaginable