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There is a specter haunting Europe — Islamic radicalism coupled with homicidal hatred of Jews.

Last weekend, French police busted up an Islamic terror cell bent on committing acts of violence against Jews. Authorities believe this is the cell responsible for an explosive device thrown into a kosher market near Paris. The ringleader was killed in the raid, and valuable intelligence captured.

If only that were the end of the story.

According to figures cited in the Israeli newspaper Haaretz, anti-Semitic acts in France increased 45 percent this year, including 101 acts of violence, graffiti and vandalism, and nearly three times that in threats.

The very same day as the French police raid, blank bullets were shot at a Paris-area synagogue. Most hideous of all was the murder spree last March, during which jihadist Mohammed Merah gunned down children and a teacher at a Toulouse Jewish day school, as well as several French soldiers.

French authorities are saying the right things. President Francois Hollande met with Jewish community leaders and pledged to fight anti-Semitism “with the greatest firmness.” He also promised beefed-up security at Jewish institutions.

France is not the only locus of rising anti-Semitism. In Hungary, the anti-Semitic Jobbik party has gained dozens of seats in parliament, while a new Anti-Defamation League poll finds a majority of Hungarians hold anti-Semitic views.

Thugs in Vienna attacked Jewish religious leaders last summer. Attacks are up in Poland and Ukraine.

In Italy this past August, citizens of the town of Affile erected a statue in honor of Rodolfo Graziani, a fascist leader known as the Butcher of Ethiopia for ordering mass executions in North Africa during World War II.

Fortunately, there is pushback against these ugly developments.

In Sweden last weekend, hundreds of Jews and non-Jews organized a “kippah march” in the city of Malmo to protest anti-Semitism in their country. The Swedish minister for European affairs was among the marchers.

In Berlin last month, after the beating of a rabbi walking with his young daughter, scores of politicians, artists and others staged a citywide “kippah flash mob,” for which they donned yarmulkes en masse.

These are welcome signs of solidarity. Such social actions, coupled with increased security, may stem the rising tide of Europe’s anti-Semitic violence.

Stem, but not stop. Even now, with the Holocaust still within living memory, the battle against the sickness of anti-Semitism continues. On the continent where history’s greatest crime took place, we must remain ever vigilant.