"The gunman on the roof was a teenaged boy, maybe sixteen years old. I could see him scanning for targets, his back to me. He held an AK-47 without a stock. Was he just a stupid kid trying to protect his family? Was he one of Muqtada al-Sadr's Shiite fanatics? I kept my eyes on him and prayed he'd put the AK down and just get back inside his own house. I didn't want to shoot him. He turned and saw me, and I could see the terror on his sweat-streaked face. I put him in my sights just as he adjusted the AK against his shoulder. I had beaten him on the draw. My own rifle was snug on my shoulder, the sight resting on him. The kid stood no chance. My weapon just needed a flick of the safety and a butterfly's kiss of pressure on the trigger. Please don't do this. You don't need to die. The AK went to full ready-up. Was he aiming at me? I couldn't be sure, but the barrel was trained at my level. Do I shoot? Do I risk not shooting? Was he silently trying to save me from some unseen threat? I didn't know. I had to make a decision. Please forgive me for this. I pulled my trigger. The kid's chin fell to his chest, and a guttural moan escaped his lips. I fired again, missed, then pulled the trigger one more time. The bullet tore his jaw and ear off. Sergeant Hall came up alongside me, saw the AK and the boy, and finished him with four shots to his chest. He slumped against the low rooftop wall. "Thanks, dude. I lost my zero," I said to Hall, explaining that my rifle sights were off-line, though that was the last thing going through my mind."