Lawton told me about the day he killed an ISIS militant. A Kurd gave him a sniper rifle to attack an ISIS-controlled village. Lawton took a position on the roof of a building and saw an ISIS fighter with a rocket-propelled-grenade launcher running below. Lawton shot him.

‘‘The guy just exploded,’’ Lawton said. ‘‘He was just gone.’’ Lawton still had the rifle at his side, close to his body like a purse.

‘‘That was my first kill,’’ he said. ‘‘Kinda weird, but I had a nightmare that night.’’

‘‘About the militant?’’ I asked.

‘‘It’s hard to explain,’’ he said. ‘‘You know these guys are animals, but even with that knowledge … ’’ He trailed off. ‘‘You know you have to let the brain figure it out on its own,’’ he said. ‘‘He pointed the R.P.G. at me. He would have taken me and my friend. It was hard for me. Killing people, you know you are here to do it. But then, when it happens, and you see it. It’s different. He just exploded.’’

We walked together up the road toward the village. Barley fields spread for miles all around us. ‘‘A couple days later, I was good,’’ he said. ‘‘Ever since then, it’s been no problem. I just have to remember the videos.”

He meant the videos of Foley, of the Syrian soldiers. He looked down and softened the earth with his boot. ‘‘See,’’ he said. ‘‘I have a big heart, and I never pictured myself actually doing it. I like to see the good in everybody.’’