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History doesn’t repeat itself, the saying goes, but it often rhymes. This week in Washington, the ugly doggerel of the present was voiced in angry and tendentious tweets from the White House. President Trump’s decision to forcibly separate migrant children from their parents at the border provoked a heated and sustained backlash, both at home and abroad. Nevertheless, even after they grudgingly moved to end the policy on Wednesday, Trump and his lieutenants continued to tar immigrants as criminals and their political opponents as the enablers of crime.

The president’s rhetoric, so baldly demagogic and polarizing, led a host of pundits and analysts to point to the echoes of a darker past, when the vilification of minorities preceded both the collapse of democracy and far more violent ends.

Accounts of weeping, terrified children crying out for their parents haunted the American media conversation. We were confronted with images of fence-enclosed "cages" and desert detention centers in the baking heat. Survivors of World War II pogroms and injustices, from the Holocaust to the internment camps for Japanese Americans, voiced their own disquiet over what the Trump administration was doing.

"It's cruel. It’s bad, and I think it sets us back in the eyes of the rest of the world that we allowed this to happen," said Jack Goldstein, whose parents sent him to a French nunnery to escape Nazi persecution, in a video produced by the Anti-Defamation League.

For some Trump critics, the moment marked an emphatic defeat for Trumpism. "In a week of brutal and evident human suffering, the wall-to-wall media coverage meant the political costs of this policy rose and rose, and Trump’s defeat was inevitable from the start," wrote Rick Wilson, an outspoken, anti-Trump Republican strategist. "When Trump signed the executive order reversing his policy on Wednesday, it was an epic political defeat for his presidency, his staff, his congressional defenders, and his media cheerleaders."

But if he felt chastened by the reaction, Trump isn’t showing it. Republicans are reportedly preparing a bill with Trump’s backing that would make it possible to keep migrant children in detention longer than 20 days. Over the weekend, Trump doubled down on his anti-immigrant messaging, convinced that his hard-line stance would aid the Republicans ahead of midterm elections in November. In a series of tweets, he even suggested that he wanted to strip migrants of due process and rights recognized by a series of international conventions.

Trump's recklessness here is not just his own. A host of allies have taken up the president's talking points, repeatedly stressing the tenuous connection between immigration and criminality.

As I wrote last week, the Trump administration's approach is shared by politicians in Europe's far right, who grandstand over the imagined threat posed by migrants and certain minorities, and vow mass deportations. Trump appeared to cheer on a far-right political challenge to German Chancellor Angela Merkel and, more broadly, has found common cause with a wide range of the continent's xenophobic, Euroskeptic parties since coming to power.

"Make no mistake, there is a concerted attack on the constitutional liberal order," said Constanze Stelzenmüller, a German scholar at the Brookings Institution, to the Financial Times. "And it is being spearheaded by the president of the United States."

And that's where the echoes of the past return. "The 1930s playbook involved scapegoating minorities for crimes they did not commit. Mr Trump says the same of Hispanics," wrote the FT's Edward Luce. "Trump’s attacks on the 'lying media' for pointing this out have strong echoes of Adolf Hitler’s demonization of the 'lugenpresse' — the lying press. The same applies to Mr Trump’s claim that 'crime in Germany is way up'" — a statement he has repeatedly made despite it not being true.

On the right, Trump's defenders justifiably bristle at invocations of Hitler and the Holocaust. But that's not the direct argument his critics are making. “I don’t believe any of these leaders are, at the moment, planning mass murder,” wrote Post columnist Anne Applebaum, referring to Trump and his far-right European counterparts. “The purpose this time is different: to define and classify a group whose existence can be used to create fear. Social media can be used to give these enemies greater numbers than they have in reality; even when they don’t exist, talk of ‘no-go zones’ and ‘crime waves’ can be used to win votes.”

Beyond stirring a narrow base ahead of elections, this fear-mongering has deeper and more dangerous effects. "Put starkly, the norms and taboos established after the world witnessed the Holocaust are eroding before our eyes,” wrote the Guardian’s Jonathan Freedland, lamenting the unraveling of the West's liberal order. "For 70-odd years, roughly the span of a human life, they endured, keeping the lid on the darker impulses that, we had seen, lurked within all of us. It steadily became taboo to voice undiluted racism and xenophobia. Those fears, those loathings of the stranger, never went away, of course. But they were held in check, partly by the knowledge of where such hatred, unrestrained, could lead."

Now, those shackles appear to be coming off. Trump's muted criticism of a neo-Nazi rally in Charlottesville, Va., last year was a watershed moment, when a sitting U.S. president seemed to initially coddle white supremacistsDuring a Fox News segment over the weekend premised on repudiating left-wing criticism of the president, David Bossie, Trump's former deputy campaign manager, referred to the "cotton-picking mind" of his Democratic interlocutor, who happened to be black. Across the pond, populist politicians in Germany, France and Italy have all urged their compatriots to stop feeling guilty about the fascist legacies of World War II, while warning of new terrors posed by migrants and Islam.

David Runciman, a Cambridge historian and author of a new book on the erosion of liberal democracies, rejects the need to invoke the 1930s when discussing the present. But he sees the deepening polarization and the rise of extremist voices as part of a broader trend.

"I don’t think people will look back on the Trump years and think either that was a complete outlier or that was the moment when everyone realized 'the change,'" Runciman told Slate. "They will, I think, look at the Trump era as part of a long story of democratic decline. So Trump for me is more symptom than the cause, and when Trump goes, democratic institutions will have been damaged and corroded."

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