Radio host Alex Jones is a big Trump fan — and Trump, for his part, has returned the favor. In December, he went on Jones’s show, telling the host, “your reputation is amazing” and promising him that “I will not let you down.”

Given that Jones is one of America’s foremost conspiracy theorists, who has been accused of sowing racial and anti-Semitic fears before, that was almost certainly a mistake. Jones proved it on the latest edition of The Alex Jones Show, aired on Tuesday, when he blamed America’s ills on “the Jewish mafia.”

“They run Uber, they run the health care, they’re going to scam you, they’re going to hurt you,” he said, per Media Matters. Jones listed a series of prominent people with Jewish backgrounds he believed to be working with this mafia — Rahm Emanuel, Madeleine Albright, George Soros — and accused them of being part of a “global, corporate combine” in alliance with the Japanese, Communists, and other evil factions.

“I guess I better do some exposés on the Jewish mafia,” Jones said. He described Emanuel as “a guy foaming at the mouth with knives at Cabinet meetings, basically threatening the president, totally crazed. Who’s got his fingers in everything, screwing us over.”

But, Jones insisted, “I’m not against Jews.” Just the Jewish Mafia, whatever that is.

The thing is, this kind of behavior shouldn’t surprise anyone. While anti-Semitism actually isn’t that common on Jones’s show, the kind of wingnut conspiracy theorizing that this segment represents very much is.

“Alex Jones is the primary producer of conspiracy theories in America today,” says Mark Potok, a senior fellow at the Southern Poverty Law Center.

Jones has repeatedly warned of FEMA plots to put Americans in concentration camps. He has labeled every major terrorist attack in the US, including 9/11, as “false flags” secretly committed by the government as pretexts to take away our civil liberties. He even, in one memorable segment, accused the government of putting chemicals in the water to turn frogs gay for some nefarious purpose.

This is who Jones is. It’s his entire thing, the whole reason for his popularity. The Trump campaign couldn’t possibly have failed to understand this before Trump went on his show. Yet Trump appeared anyway. And Donald Trump Jr. has promoted Jones’s work on Twitter at least twice.

It’s especially troubling given that Trump himself is now openly trafficking in anti-Semitic language, as my colleague Yochi Dreazen has detailed.

“Trump [has alleged] that a global financial cabal is secretly working hand in hand with the media to destroy the United States,” Dreazen writes. “Trump is using barely coded words that directly echo one of the most ancient of all anti-Semitic libels.”

So Trump’s signal-boosting of Jones isn’t funny. It’s actually quite troubling.

“It’s absolutely amazing that Trump would validate Alex Jones by going on his show,” Potok tells me, with a note of anger in his voice.

You can listen to the whole Alex Jones rant here, courtesy of Media Matters: