Watching the tragedy-turned-drama of this week unfold in Ferguson, Missouri—five hours up the road from my home in Arkansas—an eight-year-old scene kept replaying in my mind.

It was a little after dawn on Thanksgiving morning when the Afghan National Army soldiers and the Afghan National Police officers pointed their AK-47s and rocket propelled grenades at each other, jabbering threats in angry Pashto and Dari. They were about 30 feet away from where I was monitoring the radios in the passenger seat of my gun-truck. Suddenly, the hot turkey dinner my infantry platoon had been promised that afternoon at our remote outpost in the middle of Taliban-country in Ghazni province seemed pretty far away, given the inevitable turkey shoot. It had happened before, the A.N.A. and A.N.P. shooting at each other.

I set down the magazine I was reading and walked over to the tent reeking of farts and feet where the rest of my infantry platoon was sleeping to wake up my lieutenant.

“Uh, sir, the A.N.A and A.N.P. are. . . . well, you should get out here.”

Next I woke up our interpreter, who took one look at our poorly trained, trigger-happy, likely-stoned allies and said, “Fuck this shit, I go get my body armor first,” in his Hollywood-meets-Afghanistan voice. I walked back to the up-armored Humvee, shut the heavy steel-plated door as quietly as I could, got on the radio and told headquarters the fireworks would begin, oh, any minute.

My lieutenant, a jacked 24-year-old Puerto Rican guy from Queens, marched between the two groups, wearing nothing more than a t-shirt, fatigue pants and flip-flops, and pushed the barrels of the lead AK-47s to the ground. Then he grabbed an R.P.G. from the hands of a policeman, pointed, and shouted some choice phrases in universally understood English until the two factions dispersed, embarrassed and chagrined.

There’s a stale old joke—the difference between the Boy Scouts and the Army is that the Scouts have adult supervision—but on Thanksgiving Day, 2006, my Lieutenant proved that wasn’t true. As I observed the chaos in Missouri this week, I kept wondering where the adults were.

I couldn’t get past the fact that the police in Ferguson were wearing better battle-rattle and carrying more tricked-out weapons than my infantry platoon used in one of the most dangerous parts of Afghanistan. Looking at the lines of cops facing off against angry protesters, I was alarmed at their war-like paramilitary posturing.

In Afghanistan, as infantrymen facing a determined and dangerous, though largely faceless foe, our business was killing people and business was good that year. When people shot at us, we shot back until they were dead or their heads were down, then we got on the radio and dropped bombs or mortars on those heads until nothing remained but bits and pieces of bodies stuck in trees that still stood among the craters, black birds alighting on their branches for an easy meal. When people weren’t shooting at us, we passed out backpacks and sacks of rice and tried to win friends, which turned out to be a pretty hard thing to do for some reason.

To my eyes the police, whose business is peace, have no business strutting through the streets carrying M-4 carbines with reflexive-fire sights on top, surefire tactical flashlights on barrel-mounted rail systems slung from three-point harnesses, or white zip-tie flex cuffs over black-body armor, their eyes and faces obscured by gas masks and their heads covered with Kevlar helmets. A bunch of other combat veterans I stay in touch with online agreed. Indeed, besides black Americans, to whom these kind of disturbing images are hardly new, these veterans seemed the most irate, but also the most attuned to the danger posed by the cognitive dissonance of peace officers dressed for war—and not just in Ferguson, but in Boston in the wake of the marathon bombing.