Trump’s Twitter feed is offensive so frequently that it’s tempting to let oneself get inured to the horrors, to ignore as white noise his 140-character offerings.

But his retweets of Britain First videos about the purported perils of Islam, and of Muslim migration to the West, was so offensive, even by Trump’s morally debased, cretinous standards, that they merit a serious response.

Trump retweeted three video clips, titled “Muslim migrant beats up Dutch boy on crutches!,” “Muslim Destroys a Statue of Virgin Mary!,” and “Islamist mob pushes teenage boy off roof and beats him to death!” In fact, the first depicts the actions not of a migrant but of a person born in Holland, and the other two, depicting events in Syria and Egypt, are not explained in context. Regardless of the veracity of the imagery, the use to which it is being put by Britain First and now by Trump is truly vile, as the actions of depraved individuals or gangs are used by a fascist movement to deliberately tar hundreds of millions of people who have nothing to do with such crimes and would never tolerate them.

Imagine, for a moment, the unanimous outcry if Trump were to tweet, “Christian man shoots hundreds of festival goers in Las Vegas!” or “Christian mob goes on drunken rampage after Euro-cup football game!” or “Armed Christian mobs demonstrate outside mosques in Texas while other Christians firebomb Islamic centers!” He would, rightly, be condemned for tarring a whole religion with the heinous acts of a few twisted people.

That Trump was looking at a fascist Twitter feed is horrifying enough—though not at all surprising, given that he has previously paraphrased Hitler in a public speech and during the election campaign tweeted out Mussolini quotes. But that he then felt compelled to add the imprimatur of presidential authority to such vicious propaganda is unfathomable. As unfathomable as it would be if, say, Franklin Roosevelt used one of his fireside chats to broadcast the views of Julius Streicher, the monstrous but highly effective anti-Semitic propagandist in Nazi Germany.

Trump’s Twitter endorsement of Britain First’s propaganda is every bit as scurrilous. There’s nothing “mainstream” about Britain First, or about figures like Jayda Fransen, the woman who serves as deputy leader of the group and whose tweets Trump was so taken by during his early-morning online perambulations. They are, and always have been, deeply fascist in inclination and in action.

Britain First has emerged over the past few years out of the remnants of two proto-fascist groups, the British National Party and the English Defence League, both of which have been effectively driven into obscurity, or at least steep decline, by years of grassroots anti-fascist organizing. The BNP itself emerged as a splinter group from the National Front, which was founded as a street-fighting anti-black and anti-immigrant party in the late 1960s, and which caused considerable mayhem during the 1970s. Its founding was regarded by fascists in the UK as the most significant event in Britain since the disbanding of Oswald Mosley’s British Union of Fascists, under government order, during World War II.

This is the heritage of white-supremacist skinheads and racially motivated football hooligans. It is the sort of politics that regards a weaponized broken bottle as an appropriate tool with which to pursue one’s political agenda.

Such are the vicious antecedents of Britain First, a group that these days uses the Internet to troll Muslim and pro-immigrant politicians, and that routinely threatens, and sometimes commits, acts of extreme violence against its opponents. In 2016, Labor MP Jo Cox was stomped, stabbed, and shot to death by a supporter of the organization, a man who repeatedly yelled “Britain First!” during his bloody attack. That same year, Britain First activists launched “Christian Patrols” in the town of Luton aimed at personally intimidating local Muslims, especially women wearing the hijab. Fransen, who is currently facing legal actions in Northern Ireland for her hate activities, has described pro-immigrant politicians as “traitors” who will be “punished” via “good old fashioned British justice at the end of a rope.”

Any mainstream politician in the UK who retweeted Britain First tweets would be out of a job and probably expelled from his or her political party in an instant. In Britain, as in the rest of Europe, there is still an active memory of what happens when fascists, or those temperamentally sympathetic to fascist worldviews, take power. The carnage unleashed by Nazism isn’t regarded as ancient history in the continent the Nazis turned into an abattoir.

That doesn’t mean that plenty of people in France—as well as Germany, Holland, Sweden, and elsewhere in Europe—aren’t attracted to far-right parties and beliefs; but it does mean that the mainstream body politic works to marginalize such views and such groupings, and to delegitimize the hate-filled, mob-inciting messages of their leaders. That Trump, the most powerful politician on earth, retweets such moral garbage instead of condemning it, and that his party, the GOP, stands silently by while he does so, is the great tragedy, the stench, of our historical moment.

Where are those good men and women of the GOP who will rise up against this filth? Senators Jeff Flake and Lindsey Graham condemned the president’s retweets, but why are their colleagues silent? Where are the voices of conscience at this pivotal moment, as Trump wins the public praise, again, of David Duke and other pond-scum white supremacists? Where are the ones who say “enough”? You will, one day, be judged by history for your silence.