Cops never know what they are walking into, because even situations that seem calm and predictable can burst into mayhem in a moment. So nobody should ever begrudge law enforcement officers the safety precautions they take.

All the same, you have to wonder about the show of force that turned out on Convair Lane in Henrico early Monday morning. There had been some sort of dispute, and shots fired. But nobody had been hurt and the public was never in danger, according to Henrico police Lt. Lauren Hummel. Two juveniles were taken into custody.

Which makes you wonder why—even allowing for an abundance of caution—the situation required not one, but two Lenco armored personnel carriers. Or why the incident apparently called for a sniper in a ghillie suit. No doubt there are times and places when a camouflaged sniper can come in pretty handy, even for a civilian police force. But a Henrico suburb not far from Lewis Ginter Botanical Gardens?

The Lenco armored-vehicle company boasts that its BearCat "may be used as a S.W.A.T. or Military Counter Attack and Rescue Vehicle and is often used in hostile Urban Environments or as a Patrol/Reaction Vehicle on a Military Base." It comes with armor plating, bulletproof glass, gun ports, and other features, such as chemical and radiation sensors, depending on the model.

That makes it a useful vehicle to have on hand if, say, a police officer gets shot approaching a building. If he's bleeding out in the street and the shooter is still active, you don't want to two plainclothes detectives with a stretcher trying to get him to safety. Armored personnel carriers also can prove useful during riots and other forms of urban unrest.

But at what cost?

"The scene harkened to familiar images of the Iraq war: men in black helmets and body armor sitting on top of armored personnel carriers, rifles at the ready, surveying the civilian population," reported USA Today in 2014. "Except this was in Middle America and the civilian population was made up of people demonstrating with their hands up to protest the police shooting of an unarmed black teen."

The response to protests in Ferguson, Mo., reignited a long-running debate over the militarization of the police. Libertarians had been warning about the trend for years, as police departments around the country snapped up surplus Pentagon materiel or bought paramilitary equivalents from the private sector—and then began adopting military tactics such as dynamic, no-knock raids. More than 80,000 SWAT-style raids take place each year, even though their sole purpose, four times out of five, is simply to serve a warrant.

The federal government encouraged much of this, first through the prosecution of the war on drugs, and then through what is known as the 1033 program, that gave away more than $5 billion worth of military equipment, from helicopters to grenade launchers, to local law-enforcement agencies. Some agencies—including Henrico—have used Homeland Security grants for the equipment.

Much of which is flatly not needed. Caroline County, Virginia, for instance has its own armored personnel carrier—for a locality with 30,000 residents and an average of less than one murder per year. A 2014 report in the Richmond Times-Dispatch found that more than 100 Virginia localities have received federal materiel, including M-16s, grenade launchers, and more. Some of them—again, including Henrico—were highly reluctant to disclose that information.

All of the concern back in 2014 has now faded away. But the paramilitary trend in policing has not.

This might make more sense if the police were facing increasing threats. But figures from the National Law Enforcement Officers Memorial Fund show that the most dangerous year for police officers in the U.S. was 1974, when 280 were killed. The numbers have shown a long decline since then; the 2016 total was 143.

That's still 143 too many (though far fewer than the 963 people whom police killed that year). But if militarized weapons and tactics are responsible for saving officers' lives, the public ought to have some proof of causation, not mere correlation.

And if—as seems increasingly apparent—militarized police are here to stay, then other measures might be in order. As Claire Guthrie Gastanaga of the Virginia ACLU has argued, the more militarized a force is, the greater the need for civilian oversight. (Notice how you never hear demands for civilian oversight of reference librarians.)

Granted: When someone is breaking down your door in the middle of the night, you don't call the ACLU—you call the police. But what do you do when the cops are the ones breaking down the door?

This column originally appeared in the Richmond Times-Dispatch.