Donald Trump says he’ll protect America from its enemies. He’ll build a wall on the Mexican border, block Muslim refugees, and slap tariffs on China. But Trump’s latest threats against Muslim Americans, like his attacks on the “Mexican” judge in the Trump University fraud case, show that these assaults won’t stop at the border. Trump is now targeting natural-born citizens of the United States, treating them as aliens based on religion or ethnicity. He’s not building walls around America. He’s building walls within it.

When Trump went after Judge Gonzalo Curiel three weeks ago, calling him biased and underhanded because of his “heritage,” many Americans cried foul. It’s one thing to campaign against illegal immigration or even legal immigration, they noted. It’s quite another to challenge someone born in this country based on his ancestry.

The massacre in Orlando on June 12, awful as it was, gave Trump an opportunity to change the subject and mend his ways. Instead, he continued—and broadened—his line of attack. He insinuated that Muslim Americans, like Mexican Americans, were disloyal. “Since 9/11, hundreds of migrants and their children have been implicated in terrorism in the United States,” Trump declared in a statement hours after the massacre. “Hillary Clinton wants to dramatically increase admissions from the Middle East, bringing in many hundreds of thousands during a first term—and we will have no way to screen them, pay for them, or prevent the second generation from radicalizing.”

“Their children.” “The second generation.” Trump wasn’t just arguing, as he had in the past, that the refugees couldn’t be vetted. He was claiming that even if they were vetted, they still had to be kept out of the country, because their offspring might someday become terrorists. This scenario would take place in the future, possibly involving children who were not yet born and influences from abroad that might reach these children without their parents’ knowledge. Therefore, no migrant, regardless of vetting, was safe to admit.

The next day, in a prepared speech, Trump expanded on his argument:

Under the Clinton plan, you’d be admitting hundreds of thousands of refugees from the Middle East with no system to vet them or to prevent the radicalization of the children—and their children. Not only their children, by the way. They’re trying to take over our children and convince them how wonderful ISIS is and how wonderful Islam is.

Now Trump was talking about a third generation. If the children of migrants didn’t become terrorists, their grandchildren might. And even if none of them did, Muslims were still too dangerous to allow into the country, because they or their descendants might try to tell non-Muslim kids “how wonderful Islam is.”

Trump conceded that the killer in Orlando, like the male shooter in San Bernardino, had been born in the United States. But he emphasized that their parents, respectively, were from Afghanistan and Pakistan. He also pointed to the Boston Marathon bombers, whose parents had come from Central Asia. He used these cases to justify a ban not only on Afghans and Pakistanis, but on refugees from Syria, who had committed none of these crimes. In a Fox News interview after the speech, Bill O’Reilly challenged Trump’s inference. “There really isn’t any linkage that I can find, or the FBI can find, between refugees … women and children, primarily, coming here—and violence,” said O’Reilly. But Trump conceded nothing. “I don’t think you know about linkage yet,” he told O’Reilly. “What’s going to happen two years from now? What’s going to happen 10 years from now?” Trump went on: “Look at the Boston bombers. … Their family came here. And they weren’t radical when they were 6, 7 years old. And all of a sudden, they blew people up.”

The next day, June 14, Trump escalated his assault. “The children of Muslim immigrant parents—they’re responsible for a growing number … of terrorist attacks,” he declared at a rally in Greensboro, North Carolina. He continued: “Every year we bring in more than 100,000 lifetime immigrants from the Middle East, and many more from Muslim countries outside of the Middle East. A number of these immigrants have hostile attitudes.” As an example of hostile attitudes, Trump—who had warmly addressed an anti-gay Christian group just before the Orlando attack—cited Muslim opposition to homosexuality.

Trump depicted Muslims, regardless of terrorism, as a cultural threat. In a Fox News interview after the Greensboro speech, Sean Hannity asked Trump: “How do we vet somebody’s heart and ascertain if they’re coming here for freedom, or if they want to proselytize, indoctrinate, and bring their theocracy with them?” Trump replied: “Assimilation has been very hard. It’s almost—I won’t say nonexistent, but it gets to be pretty close. And I’m talking about second and third generation. They don’t—for some reason, there’s no real assimilation. And you see it all over the place.”

Since then, Trump has repeated his warnings about American-born Muslims and their children. On Wednesday, at a rally in Atlanta, he repeated his call for an immigration ban, noting that the Orlando killer “was born here, but his parents weren’t.” Afterward, Trump told Greta Van Susteren: “The second generation—if you look at this, and I’ve done actually a pretty good study on it—the second generation can be as violent or more violent than the first.” On Wednesday, in a prepared speech, he warned again of the terror threat from “recent immigrants and their children.”

Trump’s attacks on Latino, Arab, and Muslim Americans predate San Bernardino, and they extend from crime to sheer otherness. Last September, he criticized Jeb Bush for speaking Spanish. “To assimilate, you have to speak English,” Trump insisted during a Republican debate. “We have to have assimilation to have a country.” In November, at a rally in Birmingham, Alabama, Trump called for a package deal: a wall on the Mexican border and a database to track Muslims in the United States. He asserted, without evidence, that “large Arab populations” in New Jersey—“thousands and thousands of people”—had cheered on 9/11 when the World Trade Center collapsed. And he vowed to expel “anchor babies” who had been born in the United States to Mexican parents.

Trump has targeted people of other ethnicities as well. He questioned the religious integrity of Sen. Ted Cruz, citing Cruz’s Cuban ancestry. He disputed Cruz’s eligibility for the presidency on the grounds that Cruz, despite his mother’s American citizenship, was born in Canada. Trump has also challenged President Obama’s legitimacy, claiming that Obama was “born in Kenya and raised in Indonesia” and might be a Muslim. Last week, Trump suggested that Obama, in the face of Islamic terrorism, isn’t protecting America because he “has something else in mind.”

When Trump goes after Obama’s or Cruz’s place of birth, he’s challenging their legal status. But when he goes after their heritage or religion, he’s doing something subtler. It’s the same thing Trump has done to Curiel and to American Muslims: He’s attacking the second generation. He’s also appealing to white suspicions that minorities get unfair advantages. If Obama was born in this country, says Trump, “there’s a very good chance” that Obama pretended to be Kenyan in order to get into college and get financial aid. Trump has leveled similar accusations at Sen. Elizabeth Warren, claiming that she “scammed” universities by representing herself as part Cherokee. Trump routinely mocks Warren as “Pocahontas” and “the Indian.” Years ago, he questioned the authenticity of the Mashantucket Pequots, a Connecticut tribe. “They don’t look like Indians,” said Trump.

The next group on Trump’s target list might be Asian Americans. In several speeches last week, he lambasted China, Japan, Vietnam, India, and South Korea, claiming that they rip off the United States in trade, take American jobs, and don’t pay us enough for military protection. That sounds a lot like Trump’s beefs against Mexico, which he later invoked as a reason to accuse Curiel of “inherent” bias against him. Last fall, after Trump spoke in New Hampshire, a college student tried to ask him about his allegations against South Korea. The student, a Texas-born Korean American dressed in a Harvard sweatshirt, spoke in perfect, accent-free English. But before he could get his question out—and endure Trump’s subsequent rant against South Korea and Japan—Trump interrupted him with a question of his own: “Are you from South Korea?”

That’s how Trump sees the United States. If your ancestors came from Europe, as Trump’s mother did, you’re American. If they came from Latin America, the Middle East, Africa, or Asia, you’re only provisionally American. When Trump wants your vote, he’ll put a “the” in front of your ethnicity, bragging about his relations with “the blacks” or “the Hispanics.” He’ll even claim, as he did in his speech on Wednesday, that his anti-immigrant policies would help American minorities. But deep down, when there’s political advantage to be gained by dividing and scapegoating, Trump doesn’t believe in American minorities. If you’re a minority, you and your descendants will always be on probation. Don’t forget it.

Read more Slate coverage of the 2016 campaign.