In late March, Javid, a 44-year-old living in Tehran, called his sister Yasmin in Berlin. The previous year, he had quit his engineering job and started taking intensive German classes. Now, he had a request: Could she ask their cousin, who owned several businesses in Germany, if he could get him a job right away?

Yasmin knew her brother’s chances of immigrating in the immediate future were slim, not least because the German embassy in Tehran was closed indefinitely. (These names are pseudonyms; Yasmin, an acquaintance of mine in Berlin, requested that their real names be withheld for fear of reprisal against their family.) But she said, “If there is any type of opening in Germany, you will have waves and waves and waves of people coming in. There is not the slightest doubt in my mind.”

In Brussels, Ursula von der Leyen was having similar thoughts. A few days before Javid called Yasmin, the European Commission president sent a letter to the leaders of the European Union’s 27 member states. “Although for now, the conflict has not translated into immediate migratory flows towards the EU,” she wrote, “what the future holds remains unclear and necessitates the full mobilisation of every migration diplomacy tool we have at our disposal.”

In Munich, German Chancellor Friedrich Merz was also concerned, telling a gathering of industrial lobbyists, “We don’t want to experience a Syrian scenario here.”

The Syrian scenario: For Europe’s mainstream politicians, it’s the stuff of nightmares. A decade ago, then-Chancellor Angela Merkel began welcoming refugees fleeing Bashar al-Assad’s murderous rule. Ultimately, a million came — and their presence would scramble European politics for the foreseeable future.

Before the migration, the Alternative for Germany was a backbench Euroskeptic party with no representation in the German parliament. Then it seized on immigration as its defining issue and almost overnight became Germany’s largest opposition party. Today, a group that was until recently classified as a right-wing extremist organization by German domestic intelligence is, according to some polls, the most popular party in the country.

The far right cannot be defeated on migration, German politicians of the center-left and center-right have told me. The best way to neutralize the issue is to change the subject — to focus on the economy and other issues where the far right lacks credibility. But if Iranians begin flooding into Europe, there will be no changing the subject. And so, whatever you think about the moral issues around providing refuge for people fleeing bombs, privation and persecution, the politics of a mass migration would be a disaster for anyone hoping to keep the far right in check.

It’s still too soon, of course, to know just how many Iranian refugees might come to Europe. The conflict is too fresh, and the barriers to migration — both physical and political — have multiplied since 2015. But here’s what we do know: Iran’s population is nearly four times as big as Syria’s. The war has caused significant displacement within Iran. And if people start leaving the country, they’ll be looking to Europe, and nowhere more than Germany.

“I don’t think this is an exaggeration: I’d guess that about half of the Iranian population would leave if they could,” Ebrahim Afsah, an Iranian-German professor of international relations and Islamic law at the University of Copenhagen, told me recently. “Anyone who is underestimating the migratory pressure, the desire to leave this country, is fooling himself.”

The mainstream parties in Europe are widely perceived as indecisive on immigration, vacillating between co-opting the nationalist right’s position and staking out a more nuanced stance. “That basically leaves the extreme right as the only political force that at least takes the problem seriously,” Afsah said. Any further migration, he believes, will prompt “an almost guaranteed structural move toward the extreme right.”

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In early September 2015, after an arduous weekslong journey across Turkey, the Aegean Sea and the Balkans, exhausted Syrian migrants pulled into Munich’s central train station and were greeted by an astonishing sight. Hundreds of people lined the platform, holding flower bouquets, food donations and “Welcome to Germany” signs. At other stops along their caravan, the refugees had faced tear gas, water cannons and razor wire. Now, it seemed, they’d finally made it to a place where they were wanted.

A few days earlier, Merkel had uttered the three most consequential words of her chancellorship: “Wir schaffen das.” Its meaning was similar to Barack Obama’s “Yes we can,” but its implication was more specific: We, as an economically strong country of 82 million, can absorb these people fleeing untold hardship.

In the coming months, more than a million refugees would stream into Germany. Authorities rushed to accommodate them, creating tent cities and social supports. Germany’s Willkommenskultur (“welcome culture”) vastly exceeded anything its neighbors could muster.

But what started as a feel-good story began to morph. Soon, reports trickled out of sexual assaults by men of Arab and North African origin at New Year’s celebrations. Ultimately, more than 1,000 women said they’d been assaulted, principally in the city of Cologne. Many of the details remained contested, but the damage was done. To many Germans, refugees and asylum-seekers were no longer victims in need of support; they were a threat.

The AfD sensed its opportunity. While the government and media had been cautious about connecting reports of assaults to migrants, the AfD showed no such compunction. It quickly rebranded itself as the leading anti-migration voice and the protector of “our women” against invading immigrants. And politically, it worked: After falling short of the 5 percent threshold for parliamentary representation in 2013, it won 12.6 percent of the nationwide vote in 2017, becoming the main opposition party to Merkel’s governing coalition with the Social Democrats.

Two things happened next: The mainstream parties tried to head off the AfD by moving sharply to the right on immigration, but the AfD nevertheless continued to gain support. Last year, it won more than 20 percent of the vote in federal elections, good for second place. Now, recent polls show it just ahead of Merz’s center-right Christian Democratic Union for first. In elections this fall in two eastern states, it’s almost certain to finish on top and could take state-level power for the first time.

In many ways, the AfD has been pushing on an open door. About 30 percent of Germans currently have a “migration background,” as it’s commonly known here, meaning that they immigrated or have at least one parent who was born without German citizenship. It’s a difficult-to-accept reality for a country that is simply unaccustomed to such diversity, and it has unsettled Germans across the political spectrum. A generally progressive acquaintance in Berlin recently bemoaned to me that nearly one in every two children born today has a migration background. Merz was condemned by the political classes when he said last fall that migration had caused a “problem in the cityscape,” but many Germans clearly share his discomfort at being surrounded by people who don’t look or seem “German.”

And it’s not just Germany where hostility to migration has altered domestic politics. The far right is surging across Europe. In France, the National Rally is favored to win the presidency next year. In Britain, Reform UK is the clear leader in most polls; so is the Freedom Party in Austria. If the nationalist right takes over these countries, the consequences would be significant. These parties have, to varying degrees, cozied up to Vladimir Putin and rejected Europe’s efforts to bolster Ukraine; their ascension to power could meaningfully affect the outcome of that war. More generally, victories by far-right parties would represent a crushing blow to NATO and a major boon to the Trump administration, which has worked openly to build a global right-wing alliance. The ouster of Viktor Orbán in Hungary — so heartening to liberals around the world — would instantly look like an exception rather than the start of a trend. In short, what begins as a domestic concern in Germany and other European countries could quickly upend politics around the globe.

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But how likely is a wave of mass Iranian migration to Europe? Experts disagree. Austrian social scientist Gerald Knaus — one of the architects of a 2016 EU-Turkey deal that dramatically reduced the number of migrants crossing the Aegean Sea — thinks that the prospect is overblown. The notion that internal displacement within Iran will translate into mass migration to Europe, he told me, “is completely misunderstanding how this has worked in the past.” The only reason so many people were able to come to Europe in 2015, he said, was because the Syrian-Turkish border was effectively open; now it no longer is. Even talking about a potential wave, he argues, helps the far right, which “always has this dystopian vision of thousands of people at the border.”

By contrast, Naika Foroutan, the Iranian-German director of the German Center for Integration and Migration Research, thinks “a huge wave of migration from Iran” is likely. She pointed out that after the 1979 Iranian Revolution, the new regime expelled large numbers of pro-democracy activists to achieve stability — a situation that could repeat itself if the current leaders manage to end the war and strike a deal that lifts some sanctions on relatively favorable terms for Iran. “The first thing they’ll do is kick out all the people who are supposed protesters,” she told me. “If they have the deal they wanted for so many years, they won’t want troublemakers in their country anymore.” Ultimately, Afsah believes, it’s “very likely that we’ll see a repetition” of the Syrian scenario.

In the case of Syria, there was a four-year gap between the start of the war in 2011 and the moment when refugees began appearing in Europe in large numbers. The same thing, experts say, could happen with Iran. First, we’re likely to see a specific group of Iranians show up: those with work visas and family connections. It might not be a million of them, but it won’t be a small number either. “The first arrivals in Europe will come through legal means, and their numbers will be very, very considerable,” Afsah said.

Desperate centrist politicians could theoretically try to block even this legal migration, but it would require an overhaul of national and European laws, which currently allow for family reunification and for immigration by workers with specialized skills or job offers. Such a change would carry significant economic downsides: Germany and other European countries are facing a demographic cliff, with a shrinking workforce supporting a growing generation of retirees. The only viable way to make up the shortfall is through migration, and cutting off the kinds of skilled workers the continent needs would be economic suicide.

In theory, fleeing Iranians could try to go anywhere. But they will probably want to go where an Iranian diaspora already exists, and, with the United States almost certainly off limits, Germany is one of the likeliest destinations. In my Berlin neighborhood, Persian restaurants abound. An Iranian grocery store sits a couple of blocks from a Persian bookstore and café, where Germans sampling tea and sweets can be found alongside Iranians huddled over small tables, discussing the future of their country and their relatives back home. It’s easy to imagine it as a hub for new arrivals trying to orient themselves in a foreign land.

Iranians, and particularly Iranian exiles, are highly educated on the whole, but they’re surely under no illusions as to their prospects, given the stories about doctors and engineers from Africa and the Middle East driving cabs in Europe. And yet, having endured decades of brutal dictatorship and now warfare and blackouts, they may be ready to take their chances as migrants. “I was talking to my brother and mom,” Yasmin told me, “and I asked them, ‘How is the food situation? Do you have your medications?’ My brother said, ‘We have food. We have medication. You know what we don’t have? A future.’”

The irony here is cruel: Javid and his fellow Iranians face dire circumstances — fear, repression and war. But if enough of them decide to flee an illiberal, anti-pluralistic order at home, they could inadvertently help create one in Europe.

Aaron Wiener is a former Berlin bureau chief of The Washington Post.