After spending Easter Sunday and part of the following Monday angrily tweeting about a caravan of migrants heading through Central America to the U.S. and declaring that he wouldn’t support an unrelated deal to provide deportation protection for Dreamers, President Trump declared at a news conference on Tuesday that he was “preparing for the military to secure our border between Mexico and the United States” and that “we’re going to be doing things militarily” on the border—despite the fact that illegal border crossings have reached the lowest levels in decades.

The White House later clarified that the administration would be deploying the National Guard to the border, something that presidents Bush and Obama both did. Under federal law, the military can’t be used for civilian law enforcement, so in previous instances National Guard troops have been deployed to the border in support roles.

While the president’s plan doesn’t appear to be anything new, the way that he’s talking about it seems designed to appeal to the far fringes of the anti-immigrant movement. Anti-immigrant activists have long referred to immigration—and especially illegal immigration—as an “invasion,” with some advocating military responses.

William Gheen, the extremist anti-immigrant activist behind Americans for Legal Immigration (ALIPAC) warned in a press release on Monday—after Trump had tweeted about DACA but before he suggested sending the military to the border—that if the president didn’t use the military “to repel this invading caravan,” he would call for a vigilante force to do the job instead.

“If Trump does not defend America from this illegal alien caravan’s rape of our nation,” Gheen wrote, “we will call on American citizens to utilize all of our freedoms in the Bill of Rights to quickly organize and uphold Article 4 of the Constitution. We will call this effort ‘Operation American Shield.’ Either Trump uses the military to repel this invading caravan or we will call on U.S. citizens to do it.”

Far-right pundit Ann Coulter had also been urging the president to use the military against the caravan of migrants, saying on Fox News, “He can use the military. Some of us have been saying that forever.” On Twitter on Monday night, Coulter posted an article about the caravan with the question: “Why do we have a military?”

As the Southern Poverty Law Center has documented, various other Trump supporters on the far-right have latched on to this “invasion” narrative, with one right-wing website running the headline “An Army of Illegal Aliens is Marching on America.”

This kind of rhetoric has long been a part of far-right discourse on immigration.

During his failed run for a U.S. Senate seat in Alabama, former state supreme court chief justice Roy Moore said that he’d “put the military down there” on the southern border to stop undocumented immigrants. Rep. Louie Gohmert of Texas once suggested that President Obama “do what Woodrow Wilson did” in his military intervention in Mexico: “He sent John Pershing with troops into Mexico and you can read different versions, tens of thousands of national guard were put on the border and nobody came in that we didn’t want to come in. This president could do that just as well.”

Don Feder, who sits on the board of advisors of the influential immigration restrictionist group Federation for American Immigration Reform, once wrote that troops “should be stationed on our southern border with shoot-to-kill orders for anyone trying to enter the United States without a visa or proof of citizenship in hand.” He has compared the “illegal immigrants swarming over our southern border” to “the pagan armies which regularly invaded the land of Israel and were repulsed by military force.”

In a 2015 town hall meeting, Georgia Rep. Barry Loudermilk responded to an audience member’s suggestion that the military put IEDs on the border to “blow them up” by saying it was a bad idea only “because there’s a lot of Americans who work [there] and kids on the border as well.” In a presidential campaign stop that year, now-HUD Secretary Ben Carson repeatedly suggested the possibility of drone strikes on “caves and things” on the southern border.

A Republican state legislator in Georgia said in 2010 that the National Guard “ought to be armed and, if warned by leaflets dropped all over Mexico that says that we will shoot to kill if anybody crosses, and be serious about this — and if they do that then there won’t be anybody killed.”

In 2016, Oklahoma congressional candidate Jarrin Jackson said that his service in Afghanistan was like patrolling the southern border, “except for we were allowed to shoot ‘em.”

Others have gone even further, suggesting, like Gheen, that civilians take the guarding of the border on themselves. When he was running for Congress in 2014, Rep. Jody Hice said that the crisis of children fleeing violence showing up at the southern border that summer was “the reason we have a Second Amendment,” adding, “We have the responsibility as individuals and as states to step up in those areas where our federal government will not.”

In 2011, then-Alabama state Sen. Scott Beason advised people to “empty the clip, do what needs to be done” to stop immigration. The same year, a Kansas legislator suggested shooting immigrants like “feral hogs.”

NRA board member Ted Nugent has also suggested shooting immigrants on the southern border because “these are invaders, they’re invading our country.”

Of course, anti-immigrant militia groups like the Minuteman Project have been taking this rhetoric seriously for decades, forming vigilante groups that patrol the southern border. According to SPLC, in reaction to the caravan news, “Jeff Schwilk, a former leader in the Minuteman movement who now runs the anti-immigrant hate group San Diegans for Secure Borders sent an email to his supporters writing, ’Obviously this is a coordinated, organized effort by foreign criminals and open border operatives to try to infiltrate our sovereign nation.’”