Marine Le Pen, France's National Front leader. REUTERS/Eric Gaillard There's a new risk looming over Europe: right-wing nationalism.

In a note to clients on Friday, analysts at Berenberg took a look at the possibility of emerging right-wing nationalist parties running on platforms of locking down borders as a result of the huge number of refugees flowing into the EU.

Over the last few weeks, the flow of refugees into Europe, largely from Syria, has made international headlines and become a major issue for European leaders including German chancellor Angela Merkel, who has seen her popularity plummet as a result of her handling of the crisis.

As Business Insider's Natasha Bertrand outlined this week, more than 3 million refugees have poured into Turkey and Lebanon, but with conditions deteriorating in refugee camps there, many have sought passage to the EU to seek asylum.

But European leaders haven't been responding to this crisis uniformly, which Berenberg notes runs counter to the project of the EU, which is to ensure, "political cooperation and the free movement of goods, services, capital, and labour among its members."

And while Berenberg notes that this is far from the first crisis Europe has faced, the risk of anti-immigration sentiment fracturing the EU is much greater than it is in the US, where immigration has also become a hot-button issue ahead of the 2016 presidential election.

Here's Berenberg (emphasis added):

In Europe, a populist backlash against immigration is potentially more dangerous than in the US. For example, Iowa would not leave the US even if Donald Trump were to win the state in the presidential primaries with diatribes against immigrants and the politics of Washington, DC. In Europe, however, a right-wing populist backlash against immigration almost inevitably takes on an anti-EU tinge.

After all, migrants heading for one EU country often pass through other EU states first, or come from other EU members. This is part and parcel of the very openness of the EU that underpins its success. If a right-wing populist wins a national election in a major EU member with demands to "regain control over national borders" and to ignore European rules on human rights, he or she could theoretically take the country out of the union.

Refugees wait on a platform for a train at the Keleti train station in Budapest, Hungary, September 3, 2015 Leonhard Foeger/Reuters Now, Berenberg stresses that it does not see this as likely. The rise of right-wing nationalism gripping elections across Europe, rather, is what economists call a "tail risk," or something that has a remote chance of happening but would have big consequences if it came to pass.

What's really notable here, then, are two things.

The first thing is that just a few months ago, the situation in Greece — when Greece voted against the latest bailout terms offered by its creditors — the fear was that left-wing, anti-austerity governments would gain popularity across Europe and create a second act of the euro crisis that peaked in 2011-2012.

Greece's government ultimately took a bailout despite the vote, and now the pendulum seems to have swung the other way.

The second thing is that no matter how the refugee crisis plays politically in the next several months, the potential for a so-called Brexit referendum vote on whether Britain remains in the EU could become a "de facto vote over immigration rather than the commercial advantages of belonging to the biggest single market in the world," Berenberg writes.

And so then this would see the merits of EU membership hinging not on an economic but a more broadly political question.

But again, this is all a remote possibility. Here's Berenberg one last time:

We do not expect this to happen at all. Front National's Marine Le Pen is far away from taking power in France, her new Italian copycat is unlikely to win a serious national election, and Germany's Alternative für Deutschland is tearing itself apart.

But this is what's looming.