Before he opened fire in a mass shooting that killed 11 people at the Tree of Life synagogue in Pittsburgh on Saturday, witnesses say the gunman shouted, “All Jews must die.”

But the particular moment he (allegedly) chose for his massacre, and the place he chose to do it, show that what radicalized the assailant to the point of violence was a specific manifestation of anti-Semitism: blaming Jews in America for bringing in an invasion of nonwhite immigrants who would slaughter the white race.

His last post on the pro-hate-speech social-media site Gab, posted minutes before the synagogue massacre, spells it out — with a reference to HIAS, the Jewish nonprofit that resettles refugees in the United States:

HIAS likes to bring invaders that kill our people. I can’t sit by and watch my people get slaughtered. Screw your optics, I’m going in.

The obsession that appears to have tipped the gunman over the edge was a conspiracy theory insinuating that the migrant caravan currently making its way through southern Mexico, and which President Donald Trump and conservative media have treated as an existential threat to the United States, is a Jewish plot.

His response was an attack that was both anti-Semitic — an attack on Jews and Jewish values — and characteristic of Trump-era xenophobia, which is generally expressed toward Muslims and Latinos.

Some Trump officials have all but admitted that the president has seized on the caravan to motivate Republicans to turn out in the midterms. Whether or not that’s true, it’s clear that the administration had no ability (and little apparent interest) to control just how that panic took shape. (Adam Serwer of the Atlantic has a must-read essay on what specific responsibility Trump and those in his administration may bear for the delusions that pushed the assailant to murder Jews.)

Trump’s version of the caravan panic didn’t blame the Jews, but it’s not surprising, given longstanding anti-Semitic tropes, that the gunman ended up doing just that.

How anti-Semites found a way to blame the migrant caravan on the Jews

Over the past few weeks, President Trump and the conservative media ecosystem have elevated a caravan of a few thousand Central Americans into the chief existential threat facing America in the runup to the 2018 midterm elections.

The caravan is weeks away from reaching the US-Mexico border, and when it gets there, the people in it are likely to turn themselves in legally at an official border crossing to claim asylum. In other words, it’s not even remotely the national security threat Trump has painted it as being.

But the caravan panic isn’t just about the idea of a lawless mob swarming the border. Its proponents have characterized it as a deliberate, coordinated effort to undermine America in general — and Trump in particular.

Trump officials have endorsed the idea, put forth by the Honduran government, that the caravan was a political stunt by the Honduran opposition to undermine the current Honduran president. Vice President Mike Pence has gone so far as to say that it’s underwritten by Venezuela — something for which there’s no evidence.

But other conservatives, understandably, are looking closer to home. Some have said that the caravan is a deliberate effort to sway the November elections. (They hook the caravan panic to longstanding myths, endorsed by Trump, about unauthorized immigrants swaying elections by voting for Democrats.) Others have blamed Democratic megadonor George Soros — who just happens to be Jewish.

Straight out of the Protocols of the Elders of Zion. Just moments ago, Lou Dobbs guest Chris Farrell (head of Judicial Watch) says Caravan is being funded/directed by the "Soros-occupied State Department". pic.twitter.com/QBSong7uk1 — Josh Marshall (@joshtpm) October 27, 2018

Trump himself hasn’t endorsed this view explicitly. But he has encouraged the idea that domestic opponents are to blame for the caravan. When Trump says that Democrats should be blamed, he’s ostensibly saying that the Democratic minority in Congress doesn’t support efforts by immigration hawks to eliminate extra protections for children, families, and asylum-seekers coming to the US — but it’s easy to see how people who believe the caravan is literally a plot by Democrats to import people to vote illegally might not understand the nuance.

Rep. Matt Gaetz (R-FL) popularized a video of a man handing money to women waiting in a group of people to speculate that George Soros was paying caravan members to migrate to the US. Trump tweeted the video without Gaetz’s remarks or any other context as to who was doing the paying — but he certainly spread the idea that caravan members were getting paid.

Anti-Semites on the internet took the theory one step further. They portrayed the caravan as a deliberate effort by Jews writ large to invade the United States, using an image — purportedly from footage of the caravan — in which a Star of David is seen on a truck into which people are climbing:

Bowers posted conspiracy theories about this image a ton. He became convinced Jewish-backed groups were launching an "invasion" through the caravan.



The image and conspiracy were extremely prevalent on Gab, 4chan, conspiracy YouTube and parts of Twitter.https://t.co/IfelguHuXR pic.twitter.com/M971tLhyev — Ben Collins (@oneunderscore__) October 27, 2018

The Fox News segment from which this image spread didn’t call attention to the Star of David, just like Trump didn’t explicitly say that Democrats were paying people to come to the US. Conservative media turned Trump’s conspiratorial subtext into text; anti-Semitic social media subsequently turned that subtext into text.

HIAS is involved in assisting legal immigrants — but conservatives increasingly see refugees as “illegal”

The Pittsburgh gunman wasn’t targeting George Soros. He was targeting HIAS, the century-old organization that is currently one of nine federally contracted nonprofits responsible for providing housing, job placement, and cultural orientation to refugees arriving in the United States.

Before his final Gab post, he facetiously thanked HIAS for a post in which they listed groups that had supported a refugee benefit — including a congregation that met at Tree of Life. “We appreciate the list of friends you have provided,” he wrote.

Refugees have become a particularly suspect category of immigrants over the past few years, thanks to the Syrian refugee crisis. (The crisis in Syria has promoted the idea of masses of Muslim people trying to enter traditionally-white countries, and confused the categories of “people fleeing violence” and “terrorist infiltrator.”)

President Trump called Syrian refugees the biggest Trojan horse in history; his administration has slashed refugee resettlement, specifically by making it harder for refugees to come from unstable or war-torn countries in the Middle East and Africa.

The fact that refugees are by definition legal immigrants — and that the US government funds organizations like HIAS to support them for their first few months in the US — doesn’t stop conservatives from being wary.

In a recent study published in the American Sociological Review (and discussed on Vox podcast The Weeds), researchers found that conservatives, but not liberals, were much more likely to assume that an immigrant was here illegally if the immigrant was Syrian than if she belonged to other nationalities. (Syrians in the US are extremely unlikely to be unauthorized, but they’re pretty likely to be refugees.)

Furthermore, people who believed a Syrian immigrant was here illegally were more likely to say they would call police on her than people who identified a Mexican immigrant as here illegally.

Most of the organizations that do refugee resettlement are religious organizations. But HIAS’s history is different because it started as an organization to help Jewish immigrants and refugees — and is now pushing for the US to accept more victims of the current refugee crisis, who are almost never Jews and very often Muslims.

This stance puts HIAS at odds with the Trump administration when it comes to what it means to be supportive of world Jewry. To Trump and fellow Republicans, the best way to be pro-Jew is often to be pro-Israel — and the Trump administration’s close relationship with Israel’s government is built in part on a shared attack on “radical Islam.”

To HIAS and many other American Jews, however, being pro-Jew means standing up to oppression in general and distrust of foreigners in particular. It means working to resettle Syrians, even if the president is ranting about terrorist infiltration.

But anti-Semites look at the alliance between HIAS and refugees — between Jews and Muslims — and see evidence of an alliance to overpower the white race, with the faceless brown masses storming the gates and the crafty Jews on the inside opening the latch.

It would be irresponsible to pretend that the gunman marched into the Tree of Life synagogue on Saturday simply because he hated Jews. It would be equally irresponsible to ignore that Jews were the people upon whom he opened fire. Not everyone who hates Jews hates Central Americans or vice versa — but it’s not at all surprising that a person accused of killing nearly a dozen people in his hate, hated both.