A riot police officer aims his weapon while demonstrators protest the shooting death of teenager Michael Brown, in Ferguson, Mo.. (Mario Anzuoni/Reuters)

Night had just fallen in Ferguson, Mo., as I watched a standoff form on the town’s main thoroughfare. Approximately 150 protesters stood on West Florissant Avenue, their hands held up to symbolize nonviolent compliance. A hundred yards south, the six-lane avenue was blocked by a line of police vehicles, including armored SWAT carriers. The officers held assault rifles, wielded riot gear, and — absurdly in a suburban setting — wore full camouflage. The scene was surreal and terrifying.

I had gone up to Ferguson from my home nearby in St. Louis County to witness the clashes that had erupted after a white police officer killed an unarmed black teenager a week earlier. As a university researcher, I’ve traveled to study the brutality and violence in Russia’s North Caucasus, and I was stuck by the irony of driving along a familiar road to observe the chaos only a few miles away.

In Ferguson on Aug. 17, I didn’t see authorities make efforts to restore calm. Instead, they made aggressive attempts to intimidate and draw battle lines. The two sides were unevenly matched — one was dressed for peace; the other was clearly prepared for war. Ferguson has shown us how militarization of local law enforcement does more to stir chaos than to bring order.

Before the standoff, the protesters had been marching peacefully. A local church group walked behind them, singing hymns and handing out flyers that quoted the Bible on justice and mercy. Near the burnt-out Quik-Trip, now an icon of the Ferguson protests, adults and children stood along the sidewalk watching the demonstration. An old woman in a wheelchair rolled slowly by. The march passed several county police who paid little attention to the nonviolent protest.

But soon, I saw dozens of people streaming back northward. Some were crying. Several said police were firing tear gas and rubber bullets further down the street. Two protesters passed around white fabric facial-filtration masks.

I moved to the frontline of the protest, which now faced the array of military-styled police vehicles. Over a loudspeaker, an officer ordered the crowd to “leave the area.” The people near me began backing away, but almost immediately, police launched tear gas canisters towards us. A flash-bang grenade flew past my head and detonated just in front of me, interrupting my retreat. The line of police vehicles began rolling towards us and more gas was fired into the retreating crowd.

Chaos ensued. I started running to escape the sounds of shooting behind me. A protester with a loudspeaker told us to move to a nearby park, and several young people wearing shirts that said “PEACEKEEPERS” ran across the street shouting unintelligible instructions. Lost in the terrified crowd, they seemed to go unnoticed.

As I retreated northward, back up Florissant Avenue, I saw chaos and looting in those blocks that had been quiet and calm only half an hour earlier. Struggling to stay ahead of the police advance, I was rescued by a family with three children fleeing in their SUV. We were in the last car rolling through the tear gas ahead of the police. When we reached the municipal line where Florissant Avenue crosses into the city of Dellwood, the scene suddenly changed. I saw four St. Louis County Police cruisers, several county officers (in ordinary uniforms, instead of military fatigues), and dozens of protesters calmly standing side by side, watching the chaos down the street in Ferguson.

No one there understood why the police attacked. Before then, police hadn’t discouraged protesters from walking down Florissant Avenue. The midnight curfew was hours away. Prior to the police attack, neither I, nor anyone with whom I spoke, had seen any violation of the law. The only violence I witnessed resulted from a disproportionate and relentless assault by an unnecessarily militarized police force.

Since Sept. 11, 2001, the federal government has spent billions of dollars on military equipment for state and local police. In addition to Defense Department giveaways, the State Homeland Security Program — which provides funding to states for planning and training to respond to terrorism and other threats — has budgeted about $4 million for Missouri and a separate $3 million specifically for the St. Louis area. The federal Urban Areas Security Initiative, which provides funding to metro areas for the same purpose, distributed $81 million to the St. Louis area from 2003 to 2012.

And it’s not just Missouri. Since 1997, the Defense Department has given more than $4.3 billion in military equipment to local law enforcement agencies — nearly a half-billion worth last year alone. Counties across America — from Maricopa, Ariz. to Richland, S.C. — now possess tanks with 360-degree rotating machine gun turrets. Their .50-caliber bullets can penetrate buildings several city blocks away. Richland County’s sheriff dubbed his tank “The Peacemaker.”

On Saturday, President Obama rightly ordered a review of the federal programs that give local police departments easy access to this kind of military equipment. This is a good first step. Law enforcement officials may mistake their battle-field pose for community protection, but to Ferguson residents, military hardware on neighborhood streets signaled a sharp escalation of violence. Peaceful residents resented being treated indiscriminately as threats in their own neighborhoods. Wielding weapons typically used for occupation and oppression — not protection — served only to inflame the crowds.

As we rushed away from the police line that Sunday night, a black man succinctly explained to me the problem that America faces:

“It’s not a racial thing,” he said, “It’s a police thing. It’s America against the police.”