ROME • In Finland, militia groups are patrolling small towns housing asylum seekers in the name of protecting white Finnish women. In Germany, far-right protesters rampaged through Leipzig on Monday, vandalising buildings in an "anti-Islamisation" demonstration. In Italy on Tuesday, an anti-immigration regional government approved the text of a law making it difficult to construct new mosques.
The migrant crisis that has engulfed Europe since the summer is provoking new levels of public anxiety after the New Year's Eve sexual assaults in Cologne, Germany, where predatory gangs of mostly foreign men, including some refugees, reportedly groped and robbed young women.
The police say the assaults in Cologne were carried out by hundreds of men, a narrow sliver of the more than one million asylum seekers who entered Europe last year. Still, the anxieties provoked by the attacks quickly spread as reports emerged of similar assaults in other German cities, as well as in Finland and Austria.
The assaults have touched an exceptionally raw nerve as European societies face the challenge of integrating and acculturating the asylum seekers, most of them Muslims, and a majority of those single men.
Far-right political parties have pounced on the reports, having already capitalised on the inability of the European Union to secure its external borders while managing the movement of migrants.
"This has been the elephant in the room that no one is prepared to acknowledge - that the great fear is the fear of Islam," said Mr Alexander Betts, director of the Refugee Studies Centre at Oxford.
He argued that most mainstream politicians had failed to directly address these public fears or to provide enough clarity in the migration debate, creating a vacuum that anti-immigrant leaders have rushed to fill. He warned that unless leaders could quickly articulate a nuanced argument for migration, public support for granting asylum to refugees could collapse.
The public mood has been shifting for weeks. European news outlets reported on Tuesday that since Jan 1, Germany had tightened screening of migrants trying to enter the country from Austria. In Denmark, the government is even moving to confiscate valuables from arriving migrants to defray the cost of accommodating them.
Chancellor Angela Merkel of Germany has been Europe's most outspoken advocate of accepting refugees, emphasising the moral imperative of doing so while seeking to rally ordinary Germans with her slogan, "We can do it!" But critics say Dr Merkel has failed to clearly articulate a plan for an integration process that is likely to last many years.
"It seems as though the time has come for a broad debate over Germany's future - and Merkel's mantra of 'We can do it' is no longer enough to suppress it," wrote German magazine Der Spiegel, which described the police's failure to stop the Cologne assaults as "symbolic of the state's powerlessness in the face of chaos and crime".
Polls show that far-right parties are gaining support in France, Germany and elsewhere.
In Austria, Mr Herbert Kickl, general secretary of the right-wing Freedom Party, has called for an immediate halt to new asylum applications. Many Austrians who are very wary of the party's agenda concede that the influx of refugees has stirred an undercurrent of fear.
"There's a split in society - in our editorial office, at the lunch table, in circles of friends," said Mr Florian Klenk, editor-in-chief of Falter, a Vienna-based, left-leaning weekly.
Mr Peter Hacker, Vienna's appointed refugee coordinator, said the city had developed strategies to coordinate waves of migrants last September, but added: "Here in Vienna, we have a clear political stance on refugees and migrants. Vienna has understood for decades that migrants are to be helped."
NEW YORK TIMES