What did Donald Trump do today?

He told a very old, very ugly lie.

Trump's re-election campaign telescoped down this week to a single issue: convincing voters that they are in danger from protests against racism, and that he alone can fix the problems that have arisen on his watch.

In attempting to sell the idea that he personally is a victim of Americans' anger at systemic racism and police violence, Trump today reached for a slur with an ugly history. In an interview with Fox News tonight, he painted a picture of "thugs"—the Black Lives Matter movement—who were being manipulated by unnamed "ideological" paymasters. But according to Trump, the "foolish" wealthy people pulling the strings would in turn be destroyed by the "thugs."

TRUMP: We wouldn't have— they were going after Thomas Jefferson, they were coming after Lincoln, and they were going after the Washington Monument, they were gonna knock that one down. They were going after — and I actually don't even think they know, I think they're just thugs, I don't think it's — it's, it may be an ideology, and it may not. It is an ideology for the people that are paying them, and the funny thing is, and the strange thing is, the people that are paying them at all this money, cause somebody's doing it, they travel — well, wait — the people paying them, those people will be overthrown, their lives will be taken away, their lives will in danger, they're all gonna be gone. They're just stupid foolish people that made a lot of money.

Trump is fond of referring to African-Americans as "thugs," but this is as much an old anti-semitic trope as it is racist. The idea of a secret Jewish cabal stirring up trouble by funding anarchists and inciting riots among the underclass was one promoted by Nazi Germany and by American segregationists, although it's older than that. Regardless of what government is using it, the point of the story is to explain away genuine anger by the people at their leaders as the result of "agents" of the secret Jewish conspiracy sowing unrest.

Recently, though, it's found a new life in online conspiracy theories featuring the billionaire George Soros, a donor to liberal causes, which Trump has openly endorsed on quite a few occasions.

In the same interview tonight, Trump also claimed that an RNC attendee told him a horror story of traveling "on a plane from a certain city, and in the plane it was almost completely loaded with thugs wearing these dark uniforms, black uniforms with gear and this and that." Asked for details, Trump wouldn't say who had supposedly told him this story.

It's not clear whether Trump, who is easily manipulated and susceptible to flattery—he is usually cast as the hero in the modern internet-troll versions of this conspiracy theory—actually believes this, or simply thinks his supporters will if he tells them to. 

Why does this matter?

• Literal Nazi propaganda should never come from the mouth of the President of the United States.