Long before Chérif Kouachi burst into the offices of Charlie Hebdo last Wednesday with his brother Saïd to assassinate the journalists and cartoonists gathered at the satirical magazine’s weekly editorial meeting, he had a dream. Mr. Kouachi wanted, according to testimony given at a 2008 court hearing, to “burn synagogues,” “vandalize Jewish stores in Paris” and “terrorize the Jews.” We know that dream was shared by Amedy Coulibaly, the gunman who laid siege to a kosher supermarket in Paris on Friday and killed four of the terrified hostages — Yoav Hattab, Yohan Cohen, Philippe Braham and François-Michel Saada — for one reason: They were Jews.

In 2012, the French Islamist Mohammed Merah murdered three students and a teacher at a Jewish school in Toulouse. In May, the Syria-returned Frenchman Mehdi Nemmouche killed four people in an attack on a Jewish museum in Brussels.

Anti-Semitism manifested its hateful ways again last summer when synagogues and Jewish-owned shops were attacked in and near Paris after Israel’s incursion into Gaza. The destruction of Jewish businesses recalled painful images of past suffering endured by Europe’s Jews, including the violent attacks on Jewish merchants on Kristallnacht, the infamous night of Nov. 9, 1938, which was the beginning of the Nazi pogrom against Austrian and German Jews. In France, 75,000 French Jews were deported to Nazi concentration camps during World War II.

It is no wonder that feelings of insecurity and isolation have resurfaced, and that some French Jews are asking themselves if they have a future in France, home to Europe’s largest Jewish population. Many have already left for Israel — nearly 7,000 last year — and Prime Minister Benjamin Netanyahu of Israel, who attended the march in Paris on Sunday, urged more French Jews to do so, telling them: “Israel is your home.”

An exodus of Jews would suit last week’s attackers just fine. The terrorists hoped that the murder of Jews and the cartoonists who dared to sketch the Prophet Muhammad would trigger a spiral of polarizing hate and fear. Since the attacks last week, there have been more than 50 anti-Muslim episodes across France, including 21 shootings aimed at mosques and other Muslim buildings. French Muslims, too, are afraid.

Prime Minister Manuel Valls has promised that all French citizens can count on government protection of their places of worship. On Monday, Defense Minister Jean-Yves Le Drian announced that 10,000 military troops would be deployed to protect “sensitive sites” throughout France. In addition, 4,700 police officers will protect Jewish schools and synagogues.

This appropriate action backs up Mr. Valls’s statement on Saturday that “France without Jews is not France.” Claude Lanzmann, the French filmmaker best known for his powerful 1985 documentary film on the Holocaust, “Shoah,” expressed Mr. Valls’s sentiment in even starker terms in an essay in Le Monde on Monday, writing: “Let us not give Hitler this posthumous victory.”

On Tuesday, President François Hollande vowed during a ceremony to honor the three police officers killed during last week’s attacks, saying that “our great and beautiful France will never break, will never yield, will never bend” in the face of terror.

That was also the message delivered by the nearly four million people of all faiths, creeds and national origins who marched in cities across France on Sunday. Many carried placards with the now world-famous message “Je suis Charlie” — “I am Charlie.” But some carried this message of solidarity: “Je suis Juif” — “I am Jewish.”