The Charlie Hebdo attack could explode the racial and immigrant tensions that have been simmering in France for years

The terrorist attack in Paris that has left at least 12 people dead is likely to inflame racial, ethnic, and religious tensions in France and throughout Europe, experts and observers say, stemming from already simmering anti-Muslim and anti-immigrant sentiment throughout the continent.

The attack on Wednesday came at the offices of the French satirical publication Charlie Hebdo, which has been unrelenting in its decision to publish cartoons challenging religion and Islam. But it will have reverberating effects across France and other European countries, judging from some of the immediate, anti-immigrant reaction.

“Progress has been made every day throughout Europe for the past couple of years,” Demetrios Papademetriou, the president emeritus of the Migration Policy Institute, told Fusion. “This event has the potential to stop that progress in its tracks — to reverse it, even.”

Late Wednesday afternoon, police reportedly identified three suspects, according to The Guardian. But there were no immediate motives given for the attack. Some witnesses, however, told Sky News they heard the gunmen shouting that they had “avenged the prophet.”

WATCH: ‘Je Suis Charlie’: Thousands of Parisians take to the streets after terror attack

Marine Le Pen, the leader of the far-right National Front party in France whose support has surged over the past year, was the first leader to take the opening. She has built a platform on blaming an influx of immigrants for France’s growing inequality and near-record unemployment. And she has gained enormous ground against massively unpopular President Francois Hollande as the country looks ahead to the 2017 elections, with her party leading in early polls.

Part of the party’s rise to the top of those polls has been warning of the spread of Islam, a religion that an estimated 5 million of France’s citizens practice, according to the Brookings Institution — about 8 percent of the country’s population. France’s practice of “laicite” — a more intense separation of church and state than the U.S. — led to a ban of face-covering headgear in public in 2010.

On Wednesday, while Hollande pleaded for unity in an address to the nation, Le Pen called for a restoration of stricter European Union borders and the “absolute rejection of Islamic fundamentalism.”

“Time’s up for denial and hypocrisy,” Le Pen said in a video message, according to Reuters. “The absolute rejection of Islamic fundamentalism must be proclaimed loudly and clearly.”

Anti-immigrant sentiment has been rising in France for the past few years. A 2013 survey showed that 70 percent of respondents believe there are “too many foreigners in France.” 74 percent said that Islam is not compatible with French society. 77 percent believe religious fundamentalism should be a “concern” to the country. And 46 percent said the only way they believe unemployment rates could be reduced is by placing new restrictions on immigration.

“France is a place in which the anxiety about its Muslim minority continues to be extremely high — probably higher than any place I can think of,” Papademetriou said. “I cannot think of a country that has that much of a challenge with its Muslim minority.”

Over a similar time period, France has experienced a rise in anti-Semitism as tensions flared during the Gaza war. In early December, assailants attacked a French Jewish couple by breaking into their home, tying them up, and demanding money before raping the woman.

France’s leading Jewish organization, CRIF, said that anti-Semitic incidents in France last year were up 91 percent over the year before. Some French Jews are openly questioning whether they should remain in the country. Last year, France became the leading source of immigration into Israel.

Anti-Semitism has become a “portmanteau for a lot of angry people: radical Muslims, alienated youths from immigrant families, the far right, the far left,” CRIF Vice President Yonathan Arfi told The Guardian last year.

But the anti-immigrant and religious tension extends far beyond just France. In Germany, for example, thousands of people have been attracted to anti-immigrant and anti-Islamic rallies that began gaining traction in October.

The rallies in Germany, put on by Pegida — a German acronym for Patriotic Europeans Against Islamization of the West — have been condemned by German Chancellor Angela Merkel. In a high-profile New Year’s Day speech, Merkel specifically called out the group and urged Germans to turn away from it. But one rally in Dresden drew upwards of 18,000 people on Monday, the largest such crowd yet.

“The Islamists, which Pegida has warned about now for 12 weeks ago, showed today in France that they are just not capable of democracy, but rely on violence and death as a solution!” the group said in a statement on its Facebook page on Wednesday. “Our politicians want us to believe the opposite.”

Anti-immigrant and anti-Islamist parties have also gained traction in the Netherlands and in Sweden over the past few months. Papademetriou, the former president of the Migration Policy Institute, told Fusion that Tuesday’s terrorist attack is likely to be seized on by such groups in France and beyond over the next several years.

He said a tortured argument would likely resurface — whether immigrants are “assets” or “liabilities” for a country. For the past few years, he said, much of Europe has adopted the sentiment that they are assets. That feeling, he said, had begun “winning the day.” But Tuesday’s terrorist attack and other factors — the growth in unemployment and stagnant wage growth, among others — could make people change their minds.

“That argument,” Papademetriou said, “is going to rear its ugly head again.”

Brett LoGiurato is the senior national political correspondent at Fusion, where he covers all things 2016. He’ll give you everything you need to know about politics, with a healthy side of puns.