A new report from the Anti-Defamation League confirms that one of the Trump presidential campaign’s odder legacies is the revival of a strong form of anti-Semitism in American political discourse. It’s occurring most notably on Twitter, which has become a platform for the constant dissemination of various Holocaust memes and ethnic slurs.

Anyone who, like me, is both Jewish and writes about politics on the internet will have noticed this casually. But today’s ADL report is the first effort to formally quantify the anti-Semitic speech on Twitter and illustrate clear linkages to Trump and the “alt-right” movements that support him.

Their study covers the period from August of 2015 to July of 2016, i.e., mostly focused on the meat of the Republican Party primary campaign rather than the general election. It found about 2.6 million tweets containing clear markers of anti-Semitic content, that combined for a total reach of 10 billion impressions. The ADL worries that the wide dissemination of these anti-Semitic tweets “may contribute to reinforcing and normalizing anti-Semitic language on a massive scale.”

And yet despite the large scale of social media anti-Semitism, the ADL also found that it was remarkably concentrated.

Almost 70 percent of the tweets in question came from 1,600 accounts — that’s a lot of people, but it’s not exactly a mass social movement. Since one person can operate multiple accounts (and, indeed, the ADL found that 21 percent of the 1,600 had been suspended, possibly leading the proprietor to open a new account) it’s quite possible that a few hundred people are responsible for the vast majority of the anti-Jewish content.

The study also found that during this period at least over 80 percent of the anti-Semitic tweets were aimed at just 10 journalists. My personal experience has been that Jew-hating Twitter considerably expanded its target list since the summer, so it will be interesting to see if an ADL follow-up confirms that.

Trump unleashed an unfocused torrent of hate

The report also confirms the clear and obvious link between the Trump campaign and online anti-Semitism, even while gingerly noting that Trump does not personally appear to have encouraged any of this behavior:

There is evidence that a considerable number of the anti-Semitic tweets targeting journalists originate with people identifying themselves as Trump supporters, “conservatives” or extreme right-wing elements. The words that show up most in the bios of Twitter user’s sending anti-Semitic tweets to journalists are “Trump,” “nationalist,” “conservative,” “American” and “white.” This finding does not imply that Mr. Trump supported these tweets, or that conservatives are more prone to anti-Semitism. It does show that the individuals directing anti-Semitism toward journalists self-identified as Trump supporters and conservatives.

To me it’s precisely Trump’s lack of personal involvement in anti-Semitism (at least until very recently) that makes the way his campaign is stirring up anti-Jewish sentiments so fascinating. Trump quite clearly has built his political profile in large part on dislike of blacks (birtherism) and Latinos (Mexicans are rapists) and Muslims (the total ban on immigration “until we figure out what’s going on”) even while maintaining a very close relationship with an Orthodox Jewish son-in-law.

What we’ve seen from the Trump-o-verse is that many bigots do not make these same fine-grained distinctions. Once you position yourself as the leader of a white nationalist movement, you end up with a lot of anti-Semites in your followership. And Trump, tellingly, has never said or done anything to discourage this kind of behavior.

A normal campaign would be embarrassed by having its self-proclaimed fans out there every day telling Jewish journalists they hope they get sent to the gas chamber. Trump, who tweets and retweets everything under the sun, has thus far not bothered to address this with so much as a tweet, to say nothing of a broader speech or campaign aimed at denouncing these sentiments.