Authoritarian figures rarely rely on state power alone to accomplish their draconian ends. They often also mobilize the very thing that legitimate rulers are supposed to stop: private violence. That is part of how the Jim Crow South maintained its regime of racial apartheid after the abolition of slavery limited the scope of formal state action. And now President Donald Trump is dipping into that ignominious tradition to activate the white nationalists in his base to advance his border control objectives.

Trump did not pull the trigger in the El Paso carnage that killed 22 people and counting, but it's hard to deny that he has helped foment the atmosphere in which the trigger was pulled. Trump kicked off his presidential run by calling Mexicans rapists and criminals, of course. And in his rallies he teasingly encouraged his supporters to "rough up" dissenters who protested his incendiary rhetoric. Far from cooling such language after getting elected, he ramped it up. He has repeatedly referred to immigrants as an infestation and painted a lurid picture of an out-of-control southern border under attack by "invaders" that border patrol agents are powerless to stop because, as he laments, "we can't let them [the agents] use weapons." As New York's Eric Levitz points out, the unmistakable message to "trigger happy patriots" in all of this is that "we can't use weapons" but "perhaps you should."

That, of course, is precisely what the 21-year-old El Paso shooter, who reportedly wrote a manifesto that billed his attack as a "response to the Hispanic invasion of Texas," did. Although he took matters much further than Trump intended with his inflammatory rhetoric, the same cannot be said for border militias steeped in white supremacist ideology that have increasingly been doing for Trump what Trump can't do for himself.

For months now a slew of paramilitary outfits in border states have taken it upon themselves to patrol the southern border more aggressively than the government, constrained by due process and other concerns, can. "Having the most powerful person on Earth echo their hateful views may even give extremists a sense of impunity," points out Louisiana State University's Nathan P. Kalmoe.

Indeed, after Trump stoked fears of the Central American migrant caravan before the November midterms, about 100 volunteers from the Texas Minutemen, draped in camouflage suits, night-vision goggles, aerial drones, and semiautomatic weapons, holed up along the Rio Grande and conducted night vigils to supplement the border patrol. Meanwhile, the Arizona Border Recon, founded eight years ago by the notorious army veteran Tim Foley, has ramped up its raids in the Sasabe desert in search of drugs and border crossers over the last two years. And then there is New Mexico–based United Constitutional Patriots (UCP). It started patrolling the New Mexico border in February 2018 and videotaping its encounters with migrants. By its estimates, it has apprehended some 3,000 border crossers.

In one particularly egregious episode in April whose video the group brazenly circulated on social media to gain recruits, its "patriots" held 300 terrified asylum seekers—men, women, and toddlers—on their knees at gunpoint.

This was tantamount to an illegal hostage taking, and the backlash finally prompted the arrest of its leader—though not for holding up the migrants at gunpoint, but for impersonating a federal agent. The U.S. Customs and Border Patrol issued a pro-forma disclaimer declaring that it "does not endorse" enforcement action by private groups. But if that's the case, asks the ACLU's Peter Simonson, how does the agency explain photos of two border patrol agents on horseback posing on either side of masked vigilantes? "All indications are that they had a collaborative relationship with UCP and never told the vigilantes to cease and desist, even though the vigilantes were dressed up to impersonate BP officers, badges and all," he notes.

Even more shockingly, such actions have not made the group too radioactive for Trump and his allies. Indeed, notes Simonson, UCP is now working closely with We Build the Wall, an organization founded by Trump's former ultra-nationalist advisors, Steve Bannon and Krish Kobach. We Build the Wall's mission is to raise private funds to build Trump's wall. A few months ago, without obtaining any permits, it erected a short wall on private land on New Mexico's southern border and then illegally extended it across a federal road. The ACLU is challenging the extension, notes Simonson.

In the name of enforcing the law, these vigilante groups are breaking the law at every turn. Yet instead of facing the wrath of the administration, they are making friends in the highest circles; Bannon, after all, was the architect of Trump's America First campaign and served in the White House, while Kobach headed his voter fraud commission and was a serious contender as Trump's immigration czar.

By contrast, migrants who cross the border without proper authorization, a mere misdemeanor the first time around, are having their babies snatched from them under Trump's zero tolerance border policies, a practice that has continued even after a court order barred it. At the same time, the administration is cracking down on the sanctuary movement. Immigration activists such as Arizona State University's Scott Warren are being slapped with anti-harboring charges that carry a 20-year prison sentence merely for offering food and first aid to those crossing the harsh desert. Even advocates who merely speak out on behalf of the migrants aren't being spared.

All of this is reminiscent not in scale but in kind of the Jim Crow era, when southern states (and some northern ones) relied partly on unofficial private actors rather than official government channels to enforce its ideology of apartheid, allowing the white establishment to perpetrate the worst atrocities with impunity. Indeed, between 1877 and 1950, blacks suffered 4,000 documented incidents of extrajudicial lynchings for everything ranging from unproven accusations of sexual assault to speaking disrespectfully to a white man. In one case, a white mob in Blakely, Georgia, lynched a black World War I army veteran just because he refused to take off his uniform.

Even as whites went scot-free for these unspeakable crimes, blacks faced harsh punishment for minor crimes such as violating anti-vagary laws that criminalized black unemployment in order to keep blacks working for whites. In other words, the state systematically perverted the rule of law so that a combination of state action and private actors could keep blacks under its thumb.

America isn't the only country where this kind of thing has happened. To this day, Indian authorities rely on actual and tacit private violence to perpetuate the caste system. But America is supposed to be the country most dedicated to equality under the law. It is therefore distressing that Trump is violating that dedication by uncorking private movements and personal demons to further border objectives that he can't openly promote through legitimate state means.

Of course the El Paso shooter is facing the full brunt of the law and is being treated like a domestic terrorist. But the fact that it took Trump two days to condemn him for his sick ideology signals to his ilk that while man's law might be against them, higher law is with them, exactly as was happening under Jim Crow. Unless Trump fundamentally changes course, no one should be shocked at more vigilante action and El Paso–style shootings as his most militant supporters take his inflammatory rhetoric literally.

A version of this column originally appeared in The Week.