At the White House, on Thursday, after President Trump had wrapped up his remarks about immigration, a reporter in the room asked him to clarify a statement. The President had spoken, ominously, about dispatching the U.S. military to the border, where it would “do the job” of stopping a group of would-be immigrants from entering the country. “We hope nothing happens,” he said, but the military was “prepared.”

“Do you envision them firing upon any of these people?” the reporter asked.

“I hope not,” Trump said, in a tone that was more a warning than a reassurance. “It’s the military—I hope—I hope there won’t be that. But I will tell you this. Anybody throwing stones, rocks—like they did to Mexico and the Mexican military, Mexican police, where they badly hurt police and soldiers of Mexico—we will consider that a firearm.” Later, when asked what he meant about the rocks, he added, “If they want to throw rocks at our military, our military fights back. We’re going to consider—and I told them, consider it a rifle.”

A rock is a rifle, and—in an even bigger conceptual leap that Trump repeatedly makes—a caravan “is an invasion.” The migrants travelling north by foot from Honduras and Guatemala are “pretty tough people” able to “blast through the Mexican military and Mexican police,” Trump claimed. They are unknown mystery men—“a lot of young men, strong men”—geared up for an assault. (In fact, the migrants include many women and children.) He continued, “I don’t want them in our country. And women don’t want them in our country. Women want security. Men don’t want them in our country. But the women do not want them. Women want security. You look at what the women are looking for.” Less than a week before the midterm elections, Trump has returned to the image that he invoked on the day, three years ago, when he announced that he was running for President: rapists on their way from Mexico.

Trump is not subtle about the racial aspects of this appeal to fear. This week, he tweeted out a video about a man who, after being deported twice, returned to California, where he murdered a sheriff’s deputy and a detective, and later gloated about it in court. A caption said that the man had “KILLED OUR PEOPLE!”—and that this was the Democrats’ fault. Nor are there any limits, it seems, on the President’s willingness to ply the country with conspiratorialism. On Wednesday, four days after eleven people were murdered at a synagogue in Pittsburgh, by a man who reportedly believed that Jews were plotting to bring migrants into the country, and a little more than a week after another man had mailed crude explosives to several of the President’s opponents, Trump told reporters that he “wouldn’t be surprised” if George Soros, the recipient of one of those packages, had funded the caravan. Trump also said, of the caravan, in his White House statement on Thursday, “You have a lot of professionalism involved with setting up the caravans . . . and there seems to be a lot of money passing.”

The video has been compared to the Willie Horton ad, deployed during the 1988 Presidential campaign, which used racially charged imagery to blame Governor Michael Dukakis of Massachusetts for an African-American convicted murderer who committed rape and assault while on furlough. Trump has gone even further, though, with his tales of a dark-skinned foreign army of foot soldiers in T-shirts and jeans. Given the tangle of post-9/11 laws and practices that give the President greater powers on whatever he defines as “the battlefield,” calling the migrants foreigners who are invading the country by force could have consequences that go well beyond rhetoric, and even beyond the election of candidates who might owe their office to a campaign grounded in xenophobia and bigotry. Defining the undocumented as a military problem potentially weakens limits on surveillance, detention, and due process, both because of exceptions for national security built into various laws and because the courts often defer to the executive in matters of war.

Treating migrants as soldiers or terrorists would hardly be more radical than one that Trump has already proposed: ending birthright citizenship, a fundamental promise of the Fourteenth Amendment, which reads, “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the state wherein they reside.” Earlier this week, Trump said that he could abrogate that constitutional right by executive order. In doing so, he helped to bring to the surface a disturbing campaign that has been bubbling for years in conservative legal circles: to deny the plain meaning of the Fourteenth Amendment. When the amendment was ratified, in 1868, the clause “subject to the jurisdiction thereof” was intended to exclude only the children of diplomats and members of certain Native American tribal nations, and, theoretically, a foreign army that had occupied some part of the United States. Now, though, some opponents of birthright citizenship are pointing to stray out-of-context (and, at times, twisted) sentences in the Senate debate over the amendment in an effort to claim that it was really meant to exclude the children of all foreigners.

This is not only ahistorical but baffling: would the senators who supposedly understood the amendment that way not have noticed that, immediately and ever since, it was the basis for the citizenship of countless Americans with foreign parents? Other birthright truthers say that, because there weren’t any people called “illegal aliens” when the amendment was ratified—and immigration wasn’t generally restricted—it couldn’t possibly apply to them. This also makes no sense, for multiple reasons: undocumented people are still subject to our laws; immigration laws can’t erase the Constitution; and “subject to” applies to a baby born here, not to the child’s parents, who may be citizens of another country. In any event, immigration was being restricted when, in 1898, more than a decade after the passage of the Chinese Exclusion Act, at a time when some xenophobes argued that the Constitution didn’t really apply to the children of Chinese parents, the Supreme Court, in U.S. v. Wong Kim Ark, directly addressed the question of what the “subject to the jurisdiction thereof” clause meant—and found that, again, it only referred to those very narrow exceptions. (I wrote about that landmark case, and the G.O.P.’s “anchor baby” obsession, during the Presidential campaign.) The majority decision quotes that same Senate debate: