Contrary to what you may have heard, the armored vehicles that appeared on the streets of Ferguson, Missouri, during the unrest that followed the police shooting of Michael Brown did not come from the Pentagon. "Most of the stuff you are seeing in video coming out of Ferguson is not military," Rear Adm. John Kirby, the Defense Department's press secretary, told reporters last week. "The military is not the only source of tactical gear in this country."

In other words: Don't blame the military for militarizing the police. Kirby has a point. Although the Pentagon has played a role by distributing surplus gear to police departments, so have the Justice Department and the Department of Homeland Security by providing grants that can be used to buy military-style equipment. In any case, the real problem, more pervasive and insidious than BearCats or MRAPs on the streets of our cities, is the dangerously misguided urge to transform cops into soldiers, as reflected in the promiscuous use of SWAT teams.

As the acronym implies, SWAT teams originally were intended for unusual threats requiring "special weapons and tactics," threats such as rioters, shooters, barricaded suspects, and hostage takers. But what was once special is now routine. Today the most common use for SWAT teams, which are deployed something like 50,000 times a year in the U.S., is serving search warrants, typically in drug cases.

Looking at a sample of more than 800 SWAT operations carried out by 20 law enforcement agencies in 11 states during the last three years, the American Civil Liberties Union (ACLU) found that 79 percent involved search warrants. More than three-quarters of the searches were looking for drugs.

These raids tend to follow the same basic pattern: Heavily armed, black-clad men enter a home early in the morning, while the occupants are asleep. The police often break down the door with a battering ram, shatter windows, and toss in a flashbang grenade, an explosive device designed to discombobulate targets with a blinding light and deafening noise. If there is a dog in the home that barks at the invaders (as dogs tend to do), the police kill it.

The element of surprise and the overwhelming, terrifying show of force are supposed to minimize violence by forestalling any thought of resistance. It does not always work out that way.

Last December a Texas marijuana grower named Henry Magee shot and killed a Burleson County sheriff's deputy who broke into his mobile home in the middle of the night along with eight other officers. Magee said he mistook Sgt. Adam Sowders for a burglar, and in February a grand jury declined to indict him in the deputy's death.

Six months before Magee shot Sowders, a similar mistake resulted in the death of Eugene Mallory, an 80-year-old retired electrical engineer who was shot in his bed because he grabbed a gun when armed men stormed into his home early in the morning. They were Los Angeles County sheriff's deputies, looking for a nonexistent meth lab.

Last May police in Habersham County, Georgia, broke into a house in the middle of the night, looking for a meth dealer who no longer lived there. While attacking the house, the SWAT team tossed a flashbang grenade into a crib, severely burning a 19-month-old boy.

No drugs or weapons were found in that raid, which seems to be a pretty common outcome. In the ACLU study, records indicated that police found the drugs or guns they expected 35 percent of the time. The low rate of gun recovery is especially striking because the use of SWAT teams is supposedly justified by the prospect of facing armed and dangerous suspects.

The reckless use of paramilitary forces to attack the homes of unsuspecting civilians reflects a literalization of the war on drugs as well as the unseemly eagerness of many police officers to dress up and act like soldiers. Taking away their BearCats will not solve those problems.