Black Lives Matter activists protesting police violence and the killing of Michael Brown were met with heavily armed officers during the Ferguson protests in 2014. Indigenous people and environmental activists protesting the Dakota Access Pipeline faced a similar scene in 2016 when militarized law enforcement used violent tactics against the peaceful demonstrators.

Scenes of heavily armed police forces are becoming more common across the country. New research from Ryan Welch, Jack Mewhirter, Casey Delehanty and Jason Wilks finds that this militarization results in more individuals killed each year by law enforcement. The study found that twice as many people are more likely to die in counties that receive an influx in military equipment. Additional research conducted in 2016 also found that police are more likely to be attacked when they are militarized, which raises the question of how beneficial it is to pad police forces with military-grade weaponry.

The researchers looked to anthropologist Peter Kraska to define militarization as the "embrace and implementation of an ideology that stresses the use of force as a good way to solve problems.” The definition encompasses four dimensions of militarization: material, cultural, organizational and operational. Researchers argue that providing law enforcement agencies with more military equipment also increases militarization along cultural, organizational and operational lines. “Militarization makes every problem—even a car of teenagers driving away from a party—looks like a nail that should be hit with an AR-15 hammer,” the researchers wrote.

The militarization of police leads not only to more civilian deaths, but to the deaths of animals as well. To prove that high levels of violence were not the cause of an increase in militarization, researchers argued that more pets would be killed by police in areas where officers are more prone to violence. Their theory was correct: Data from the Puppycide Database Project tracking police shootings of pets found that officers kill more animals in counties where law enforcement receives more military equipment.

A 2014 study by the American Civil Liberties Union also found that militarizing police forces has a disproportionate impact on communities of color. In cases where a SWAT team was deployed to execute a search warrant, more than half of the people impacted were people of color, mainly black and Latino. Furthermore, black people were more likely than white people to be impacted by a SWAT raid.

The transformation of U.S. police agencies into militarized forces is primarily rooted in the 1996 National Defense Authorization Act signed by President Bill Clinton. The bill led to the formation of the 1033 Program, which allowed the defense secretary to provide local law enforcement with the Department of Defense’s excess military equipment at no cost. Since the bill’s passing, military equipment given to police agencies has skyrocketed.

In 1998, an estimated $9.4 million in equipment was given to 290 law enforcement agencies. The 9/11 attacks and subsequent war on terror escalated the transfer of military equipment. According to the Post, 3,029 law enforcement agencies received transfers valuing close to $800 million by 2014. And between 2006 and 2014, police forces received military equipment over $1.5 billion, including 6,000 mine-resistant, ambush-protected vehicles and 79,288 assault rifles. A study from NPR shows that armored vehicles are the most expensive category of equipment transferred under the 1033 program, totaling up to $699 million. And in addition to a bevy of equipment, military-style police raids have also increased in recent years.

In an effort to stymie the rapid flow of military equipment to police—particularly after images surfaced of heavily armed officers clashing with protesters in Ferguson, Missouri—President Barack Obama signed Executive Order 13688 in 2015 to prohibit the military from sending particular types of equipment to law enforcement agencies and regulating other transfers. The items included Humvees, aircraft, riot shields and helmets. The executive order caused these transfers to slow and equipment recalls to increase, according to the Post.

With Donald Trump now in the White House, the militarization of the police could rapidly increase again, particularly given Trump’s enthusiastic support of law enforcement. The National Fraternal Order of Police, the country’s largest police union that endorsed Trump during the presidential election campaign, published a document of potential actions Trump could take during his first 100 days in office. The first item on their wish list was for Trump to rescind Obama’s Executive Order 13688. Although Trump has not canceled the order, his penchant for law-and-order policing makes it seem likely that the police union's wish will be fulfilled.