Police militarization and border militarization go hand-in-hand. It's important to recognize this connection in the wake of two decisions recently made by President Donald Trump: to restore a program that provides surplus military gear to local law enforcement agencies, and to end the Deferred Action for Childhood Arrivals (DACA) program, which protects young undocumented people who meet certain qualifications from being deported. Both decisions represent a reversing of course on policy enacted by President Barack Obama.

Trump is an advocate of President Dwight Eisenhower's deadly immigration campaign from the 1950s, "Operation Wetback" (a title that many consider racist). He has stripped nuance from a complicated conversation by framing immigrants — especially those from Mexico — as gangsters and rapists, when many who cross the border are nonviolent people who come to the U.S. in search of safety from violence in their home countries. Attorney General Jeff Sessions, who made the DACA announcement on Trump's behalf, employs the same logic as the president, but 91% of DACA recipients are employed, and may are well-educated.

When people are kicked out of the U.S., they often try and return. Each year, border security agents stop thousands of people attempting to reenter through the U.S.–Mexico border after being deported. In 2015 alone, 15,715 people were convicted of attempting to illegally reenter the country, according to the United States Sentencing Commission. While the overall number of convictions has been on the decline since 2011, attempting to eject nearly 800,000 people has the potential to create a rush of repeat crossers putting themselves in harm's way. In a span of weeks, Trump has moved to expose these once-protected people not only to potential deportation, but also to the U.S.–Mexico border militarization industrial complex, which was supported by the reversal of the ban against surplus military gear, as it supplies border agents and law enforcement agencies in border communities with weapons, vehicles, and gear.

In its modern form, the militarization of police in the United States started in 1990, after Congress authorized the National Defense Authorization Act, which had a section that gave the Department of Defense a green light to transfer surplus military equipment to federal and state agencies. According to The Atlantic, the legislation was passed to aid the "war on drugs," but the program was expanded in 1997 to include efforts to fight terrorism, when it became known as the 1033 Program.

The attacks on September 11, 2001 led to the creation of the Department of Homeland Security (DHS), which then provided local and state police with access to grant programs to combat terrorism that even dwarfed the 1033 Program. The State Homeland Security Program and the Urban Areas Security Initiative have allowed millions of dollars to make their way to individual state and local departments, financing that can come in addition to military surplus supplies provided to departments by the 1033 Program, with the surplus transfers provided free of charge. Since 1997, more than $5 billion worth of military-grade equipment has been transferred from battlefields to local law enforcement through the 1033 Program, according to USA Today, which, based on data collected by OpenTheBooks.com, included 625 mine-resistant vehicles; 329 armored trucks and cars; 83,122 M16/M14 rifles; 1,385 riot 12-gauge shotguns; 18,299 night-vision sights, sniper scopes, binoculars, goggles, and infrared and image magnifiers; and 57 grenade launchers — all between 2006 and 2015 alone.