KANDAHAR, AFGHANISTAN—After asking why the United States was in Afghanistan in the first place, 18-year-old U.S. Army Pvt. Josh McCombs received a frank description of the terrorist attacks of Sept. 11, 2001, from Master Sgt. Todd Brinkman, 33, between raids on Taliban insurgents Tuesday. “Turns out, the little shaver was only 7 back then, and his folks didn't want him to see the horrible pictures on TV,” the commanding officer later told reporters. “Then Pvt. McCombs asked: ‘If 9/11 happened more than 10 years ago, why are we here now?’ And that’s when I told him to stop asking questions and just follow orders.” McCombs was last seen explaining 9/11 to his fellow young infantrymen, who all reportedly asked the same follow-up question McCombs did.