President Trump’s intent is not subtle.

When Trump tweets, as he did Monday morning, that “criminals and unknown Middle Easterners are mixed in” with the caravan of migrants that crossed into Mexico over the weekend, you know what he’s getting at. He’s getting at the same thing he’s been getting at since June 16, 2015, when he walked up to the microphone at his campaign launch in Trump Tower and proceeded to excoriate immigrants from Mexico as criminal by default. He’s getting at the same thing he got at in December that year, when he called for a ban on Muslim migrants to the United States, implying that Muslims were inherently dangerous in other ways. It was his campaign platform explicitly: I will protect you from the scary things out there in the world — and here are some things to be scared of.

To those who’ve been reporting on the caravan, the announcement of infiltration by criminals and “Middle Easterners” came as a surprise. Out of a group of several thousand, there are likely to be some people who have committed crimes. As for the alleged “Middle Easterners,” reporters have expressed some bafflement.

There were some people from Bangladesh in the caravan who had been detained, according to a Daily Caller report citing a reporter from Univision. The Daily Caller report seemed aimed at bolstering the president’s tweet, including a section noting the existence of terrorism linked to Islam in Bangladesh. But, of course, Trump didn’t technically say terrorists — he said “Middle Easterners,” and, if nothing else, Bangladesh isn’t in the Middle East.

There have been reports centered on the caravan claiming that the Islamic State has a presence in it. They appear to be focused on comments from the president of Guatemala, who, over the weekend, said that the country had captured 100 Islamic State terrorists but did not identify where or when. Right-wing sites quickly connected that claim to the caravan that was passing through Guatemala, often willfully blurring the two together.

(Politico’s Blake Hounshell made a valid point about this: If you’re an Islamic State terrorist from the Middle East, why would you join one of the most public and scrutinized migrations northward if you’re seeking entry to the United States?)

Asked why he’d made the assertion, Trump offered an ironic response: “Take your cameras, go into the middle, and search” for them, he said. Trump has spent several weeks insisting that first his Supreme Court nominee Brett M. Kavanaugh and then the Saudi government should be considered innocent until proven guilty of allegations each faced. Here, as in June 2015, the presumption is guilt and the proof of innocence is up to others.

Again: The intent of Trump’s tweet about the caravan is not subtle. Illegal immigration is the biggest problem identified by Republicans in a recent Pew Research Center survey, making the existence of the caravan a potent political tool. But with his tweets, Trump is also hoping to repeat an effective tactic for Republicans during the past two cycles: Make the election about fear of immigrants surging across the border.

In 2014, the fears were twofold. First was the Islamic State itself, often referred to as ISIS, which had surged into the public imagination with gruesome killings. Then, about a month before the midterm election that year, the Ebola virus reached the United States, overhauling the American public’s fear hierarchy. Cable news networks quickly switched from one topic to the other — and then, after the election, mostly stopped talking about both of them.

(Philip Bump/The Washington Post)

In part, that was because the threats evolved or waned in the United States. In part, of course, it was also because their utility in the political conversation evaporated after the election was over. The threat of Ebola-infected or terrorism-sympathetic migrants — or both? — crossing the border was raised regularly by Republican candidates, however unlikely. (Among those using Ebola to criticize the administration of Barack Obama was Donald Trump, who advocated, among other things, barring any entry into the United States from West Africa.)

The total number of people who contracted Ebola in the United States and died in 2014, combined with the number of Americans killed by terrorists from the Islamic State that year, was zero.

Two years later, Trump deployed the rhetoric of fear more directly.

“I have a message for all of you: The crime and violence that today afflicts our nation will soon — and I mean very soon — come to an end,” Trump said while accepting his party’s nomination in July 2016. “Beginning on January 20th, 2017, safety will be restored.”

What was the “crime and violence” afflicting the United States? Per Trump’s speech, it was “the attacks on our police, and the terrorism in our cities.”

“The number of police officers killed in the line of duty has risen by almost 50 percent compared to this point last year,” he said. “Nearly 180,000 illegal immigrants with criminal records, ordered deported from our country, are tonight roaming free to threaten peaceful citizens. The number of new illegal immigrant families who have crossed the border so far this year already exceeds the entire total from 2015.”

There are plenty of asterisks to those assertions, but the politics were clear. On Election Day, Hillary Clinton won voters whose biggest concern was the economy. Those who identified immigration or terrorism as the biggest issue facing the country — about 3 in 10 voters — backed Trump by 31 and 17 percentage points, respectively.

Trump has spent most of his presidency focused on what he presents as his successes — mainly the strength of the economy. But contentment is not a powerful motivator for voters. Now Trump presents a country that’s under threat. Immigrants surging to the border, terrorists embedded among them. Angry Democratic mobs intent on turning the United States into Venezuela, as he likes to say. It’s a tricky balancing act, arguing that the nation is at risk even as he is its steward.

But from a political standpoint, it’s so unsurprising as to have been predictable. Nearly Trump’s entire career in politics has been about presenting a tough face to a perceived threat.

Usually, though, that fear is only indirectly tied to politics. In another tweet Monday morning, Trump dropped whatever subtlety might have existed before.

If you’re wondering what his reelection campaign will focus on in the final weeks, we have a guess.