The news that one of the assailants in the Paris attacks may have crossed into Europe with refugees fleeing Syria is raising the fierce debate over Europe's immigration policy to a new pitch.
Chancellor Angela Merkel, already under pressure from political foes and allies, seemed Saturday to hold onto her stance of placing no limits on the number of people Germany is willing to give refuge to — a stance that is increasingly being called into question.
In a somber statement hours after the attacks, she urged her countrymen to uphold European values of humanity and compassion in the face of terror.
"We believe," she said, "in the right of every person to seek happiness and to enjoy it, in the respect for others and in tolerance."
But her optimism, reflected in Merkel's signature phrase that "we will manage it," is being met with growing skepticism in Germany and abroad, and not just by those on the far right who have long opposed immigration.
Even before Friday's attacks in Paris, Finance Minister Wolfgang Schaeuble, a close Merkel ally, likened the more than 750,000 migrants who have come to Germany this year to an avalanche. His words reflect fears not just about how long the country of 80 million can keep up its open-door policy, but also about a possible violent backlash.
The country has already seen surge in attacks against migrants and refugee shelters. So far this year authorities have recorded 689 such incidents — more than three times the number for all of 2014.
The violence has been accompanied by a sharp shift in tone.
Just a few months ago, newspapers were full of reports about refugees being warmly received at German train stations, according to Joachim Trebbe, a communications researcher at Berlin's Free University. Now reports about migrants are automatically linked to the word "crisis" as authorities struggle to cope with tens of thousands of arrivals each month.
In the meanwhile, politicians, journalists and refugee activists in Germany have been deluged with hate mail. Merkel and members of her government have been branded "race traitors," and death threats — in the form of gallows bearing her name — were paraded during anti-immigrant demonstrations.
Nazi comparisons, once considered beyond the pale of political discussion in a country still grappling with its genocidal past, have become a common slur.
Far-right extremists are behind much of the organized incitement, and have carried out some of the most high-profile attacks, including the one on Cologne mayoral candidate Henriette Reker. She was stabbed in the neck while campaigning in mid-October by a man who said he wanted to take a stand against refugees. Reker, who won the election, had been in charge of housing migrants in the western city.
Thomas de Maiziere, the country's interior minister, told reporters Saturday following the attacks in Paris that German security agencies were keeping a close eye not only on Islamic extremists "but also the far-right extremists who might react to such an attack."
But Germany's top security official also has warned that two-thirds of suspects linked to attacks on refugees and asylum homes were previously unknown to the police.
Sensitive to the growing misgivings among many Germans about how their country can cope with the sheer number of immigrants, the government recently agreed on measures to quickly process those who stand little chance of getting asylum, vetting more people at the border, and distributing migrants across Europe.
Such efforts don't go far enough, even for some of Merkel's allies.
Markus Soeder, a member of Bavaria's regional government, called Saturday for still greater efforts to ensure that authorities know who is entering the country. In an interview with weekly Welt am Sonntag, Soeder insisted "the days of unchecked immigration and illegal entry can't continue. Paris changes everything."
His warning came as a Greek official said a Syrian passport was found at the scene of one of the Paris attacks and its owner crossed into the European Union through the Greek island of Leros in Oct. 3.
If true, it wouldn't be the first time that a terrorist has slipped into Europe posing as a migrant.
A Tunisian man sent back home after serving a seven-year prison term in Italy on terrorism charges returned to the country on a migrant boat. Mehdi Ben Nasr arrived in Lampedusa, Sicily, on Oct. 4 and was expelled again a week later. He had been convicted in Italy for being part of a network of Islamic extremists who recruited fighters to go to Iraq.
Interior Minister Angelino Alfano said it would be "counterintuitive" to think that terrorists wouldn't try to infiltrate Europe along migrant routes.
Incidents such as those will make it harder for Merkel to rally Germans — much less the rest of Europe — behind her stance on immigration.
On Saturday, Poland's incoming minister for European affairs said his country couldn't go ahead with EU decisions on immigration and accept refugees without guarantees of security.
"This is a key condition that today was put under a giant question mark in all of Europe," said Konrad Szymanski.
Marine Le Pen, leader of France's National Front party, called for authorities to expel immigrants who are in the country illegally.
Asylum seekers fleeing war and poverty in Syria and other war-ravaged countries condemned the Paris attacks, saying they feared it may become more difficult for the refugees to start new lives in Western Europe.
Zebar Akram, a 29-year-old Iraqi man, was among those streaming through Slovenia toward Austria on Saturday. He said those attacking Paris were behaving "like they act in Syria or Iraq."
Abdul Selam, 31, who was fleeing Syria, said he fears refugees now "will be considered as probable attackers."
Merkel's deputy warned Saturday against cracking down on migrants coming to Europe because of the Paris attacks.
Vice-Chancellor Sigmar Gabriel said those seeking refuge in Europe shouldn't be made to suffer just because "they come from those regions where terror is being exported to us and to the world."
"We stand to protect them too, and to ensure that they don't have to suffer because murderers in France are threatening people and Europe in the name of a religion," he said.
Eldar Emric in Sentilj, Slovenia, and Demetri Nellas in Athens contributed to this report.