From the New York Times news pages:

Anti-immigrant attitudes have been on the rise in recent years in Europe, propelled in part by a moribund economy and high unemployment, as well as increasing immigration and more porous borders.

Olivier Roy, a French scholar of Islam and radicalism, called the Paris assault — the most deadly terrorist attack on French soil since the Algerian war — “a quantitative and therefore qualitative turning point,” noting the target and the number of victims. “This was a maximum-impact attack,” he said. “They did this to shock the public, and in that sense they succeeded.”

“This is a dangerous moment for European societies,” said Peter Neumann, director of the International Center for the Study of Radicalization at King’s College London. “With increasing radicalization among supporters of jihadist organizations and the white working class increasingly feeling disenfranchised and uncoupled from elites, things are coming to a head.”

LONDON — The sophisticated, military-style strike Wednesday on a French newspaper known for satirizing Islam staggered a continent already seething with anti-immigrant sentiments in some quarters, feeding far-right nationalist parties like France’s National Front.

In Sweden, where there have been three recent attacks on mosques, the anti-immigrant, anti-Islamist Sweden Democrats party has been getting about 15 percent support in recent public opinion polls.

Paris was traumatized by the attack, with widespread fears of another. “We feel less and less safe,” said Didier Cantat, 34, standing outside the police barriers at the scene. “If it happened today, it will happen again, maybe even worse.”

Mr. Cantat spoke for many when he said the attacks could fuel greater anti-immigrant sentiment. “We are told Islam is for God, for peace,” he said. “But when you see this other Islam, with the jihadists, I don’t see peace, I see hatred. So people can’t tell which is the real Islam.”

… The mood among Parisians near the scene of the attack Wednesday on the newspaper Charlie Hebdo was apprehensive and angry. “There’s no respect for human life,” said Annette Gerhard.

“Politically, the official left in France has been in denial of the conflict between France and the Arab world,” Professor Hussey said. “But the French in general sense it.”

The attack left some Muslims fearing a backlash. “Some people when they think terrorism, think Muslims,” said Arnaud N’Goma, 26, as he took a cigarette break outside the bank where he works.

Samir Elatrassi, 27, concurred, saying that “Islamophobia is going to increase more and more.”

“When some people see these kinds of terrorists, they conflate them with other Muslims,” he said. “And it’s the extreme right that’s going to benefit from this.”

The German interior minister, Thomas de Mazière, told reporters on Wednesday: “The situation is serious. There is reason for worry, and for precautions, but not for panic.”

With each terrorist attack, however, the acceptability of anti-immigrant policies seems to reach deeper into the mainstream. In Britain, for example, which also has a large Muslim population, the U.K. Independence Party has called for a British exit from the European Union and sharp controls on immigration, emphasizing what it sees as dangers to British values and identity. The mainstream parties have competed in promising more controls on immigration, too.

“Large parts of the European public are latently anti-Muslim, and increasing mobilization of these forces is now reaching into the center of society,” Mr. Neumann said. “If we see more of these incidents, and I think we will, we will see a further polarization of these European societies in the years to come.”

Those who will suffer the most from such a backlash, he said, are the Muslim populations of Europe, “the ordinary normal Muslims who are trying to live their lives in Europe.” …

The mood of failure and paralysis is widespread in France. The Charlie Hebdo attack came on the publication day of a contentious new novel, “Submission,” by Michel Houellebecq, which describes the victory of Islam in France and the gradual collaboration of the society with its new rulers from within. Mr. Houellebecq, like the well-known caricaturists and editors who were killed at Charlie Hebdo, has been a symbol of French artistic liberty and license, and his publishers, Flammarion, were reported to be concerned that he and they could be another target.

But the atmosphere has been heightened by the rise of the National Front and its leader, Marine Le Pen, who runs ahead of the Socialist Party in the polls, campaigning on the threat Islam poses to French values and nationhood.

There was much recent attention to another best-selling book by a conservative social critic, Éric Zemmour, called “The French Suicide,” attacking the left and the state for being powerless to defend France against Americanization, globalization, immigration and, of course, Islam. Another new novel, by another well-known French writer, Jean Rolin, called “The Events,” envisions a broken France policed by a United Nations peacekeeping force after a civil war.

“This attack is double honey for the National Front,” said Camille Grand, director of the French Foundation for Strategic Research. “Le Pen says everywhere that Islam is a massive threat, and that France should not support attacks in Iraq and instead defend the homeland and not create threats by going abroad, so they can naturally take advantage of it.”