I was as shocked and horrified as anyone at the news that 11 of my fellow Jews had died in Pittsburgh at the hands of a monster whose face may have changed, but with whom we are tragically and intimately familiar. But I was not surprised.

As early as the 2016 election, I had from time to time gone trawling in the fever swamps of the internet, to the various alt-right and neo-Nazi websites that inspired the Pittsburgh murderer, may his name be erased. Over time, something became increasingly clear: that there was a precipitous rise in right-wing antisemitism underway in the United States, and yes, it was deeply connected to the campaign of future President Donald Trump.

No, Trump is not himself an antisemite. He certainly did not pull the trigger at the Tree of Life synagogue. He is not responsible in any direct sense. Yes, the killer apparently despised Trump for having Jewish children and grandchildren, as well as Jewish advisers. Yes, Trump has in many ways been very good for Israel. Yes, there are plenty of antisemites on the left, and even more in the Muslim world. Yes, Louis Farrakhan, Linda Sarsour, Jeremy Corbyn, and many others are racists and would be shunned in a more functional society.

Yet it is nonetheless clear that the demented subculture that fed the murderer’s hatred and slowly incited him to violence for the most part worships Trump. And Trump has not done nearly enough to address the problem.

Almost from the instant that he declared his candidacy, Trump attracted a cult-like following on the alt-right, and especially among its online denizens. In his announcement speech, Trump’s denunciation of illegal immigration, including calling many of them “rapists,” started a firestorm. His pledge to build a wall on the Mexican border, ban citizens of Muslim-majority countries from entering the US, and numerous other well-known provocations quickly convinced the alt-right of one thing: they had found their man.

For the first time in generations, the alt-right and white nationalists felt the wind at their backs. They came out of the closet, saying and doing things that social stigma would previously have made unthinkable. The fervor became so intense that a meme developed referring to Trump as “God-Emperor.” The storm intensified after Trump’s election, when one white supremacist leader told a crowd, “hail Trump, hail victory!” a literal translation of the Nazi sieg heil. Most notoriously, hundreds of alt-righters marched in a Nazi-like torchlight procession in Charlottesville, and one deliberately ran down a counter-protester.

In the face of this, one regrets to say, Trump did little, and what little he did only exacerbated the situation. He doubled down consistently on his race-baiting rhetoric, told far-right celebrity Alex Jones “I will not let you down,” and seemed disturbingly unfazed by Charlottesville, saying that there were “good people” on both sides. To this day, he has not publicly and unequivocally denounced the alt-right, allowing them to continue their slavish devotion to him and enjoy the at-least tacit legitimacy that just a few years ago would have been unthinkable.

More generally, Trump’s assault on basic American political, cultural, social, and rhetorical norms has inadvertently aided the alt-right cause. Last year, I interviewed former ADL leader Abe Foxman, who told me that the real problem with Trump was that he had destroyed civility, and civility in and of itself is a shield for minorities, closing the Overton Window to the darker impulses of the majority. There is no question that things that previously could not be said in polite company are now being screamed, and very few of them are good. Into this sudden vacuum rushed the alt-right.

This is both disturbing and very, very bad for the Jews. Because whatever else the alt-right may be, it is viciously, murderously antisemitic. From neo-Nazi chat rooms to pickup artist websites to anti-feminist manifestos to white supremacist rock songs, the alt-right universally embraces everything from the most debased and vulgar conspiracy theories about Jews and Jewish power, to sophisticated pseudo-intellectual arguments such as that formulated by antisemitic academic Kevin MacDonald’s Culture of Critique, which charges the Jews with imposing liberal values that destroy white societies as a “survival strategy.”

Throughout, the Jews are damned as, among other things, ugly, sexually perverted, avaricious, conspiratorial, and a direct threat to Western society and the white race. There is no doubt whatsoever that it is these ideas that led directly to the Tree of Life massacre. The alt-right’s claim, for example, that the Jews are deliberately flooding white nations with non-white immigrants in order to destroy Western societies and commit a “white genocide” was specifically cited by the Pittsburgh killer as his primary motive. It was alt-right ideology that incited him to murder.

In Trump’s failure, deliberate or otherwise, to stand up to the challenge of this ideology, the president does bear some measure of responsibility for what happened at the Tree of Life synagogue.

Out of expediency, indifference, or simple contrarianism, he has not done enough to stop a hideous disease from festering and spreading, to the point that it has now taken 11 Jewish lives. This is, at best, conduct entirely unbecoming of a president and dangerous to Jewish life in the United States. The president must stand up and absolutely, unambiguously, and explicitly reject and condemn the alt-right by name in the strongest possible terms. A failure to do so would be a betrayal of the American Jewish community and the Pittsburgh martyrs, some of whom were his supporters.

After Yitzhak Rabin was assassinated, Benjamin Netanyahu looked directly into a television camera and told those who might have supported the murder, “I don’t want your votes!” Trump must now do the same — and mean it.

Benjamin Kerstein is The Algemeiner’s Israel correspondent.

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