Updated 1 year, 11 months ago

World United in Paris

Hundreds of thousands of people poured into the streets of Paris to join top French officials and world leaders for a rally and march under extraordinary security in a government-sponsored show of unity and defiance after a series of terrorist attacks.

The somber march began shortly after 3 p.m., with a vanguard of dark-coated leaders marching arm-in-arm down the broad Boulevard Voltaire. Familes of the victims walked grim-faced, some wearing Charlie Hebdo headbands to commemorate the journalists murdered on Wednesday.

The French government mobilized hundreds of military forces, police and antiterrorism squads to provide security at the rally. In the area around the Place de la République, where the march was starting, snipers could be seen on rooftops, and security officers were seen checking sewers for explosives. The police swarmed the area, and several subway stops and streets were blocked off.

Officials said that public transport in Paris would be free all day Sunday to encourage participation in the march.

At the Place de la République, demonstrators waved French flags and several climbed the imposing Statue of the Republic, a symbol of the French Revolution, and wielded an inflated pencil, symbolizing solidarity with the fallen cartoonists at Charlie Hebdo, the weekly magazine that was attacked last week.

People displayed flags from across Europe and many held signs saying, “I am Charlie.” Others held up caricatures from the magazine.

Prime Minister Manuel Valls declared on Saturday that France was at “war” with radical Islam after harrowing attacks that claimed the lives of 17 victims. Three gunmen who said they were acting on behalf of Al Qaeda and other radical Islamist groups were killed by the police on Friday in two separate raids. One gunman had taken hostages at a Jewish supermarket in Paris, and the two others had holed themselves up in a print shop in Dammartin-en-Goële, northeast of the French capital.

“Indignation. Resistance. Solidarity. I am Charlie” read an invitation to the event that was circulating on social media. The organizers said the rally was to show support for freedom of the press and freedom of speech, and to reinforce the message that France and the French would not be cowed by terrorists.

Officials from across Europe and elsewhere, including Chancellor Angela Merkel of Germany, Prime Minister David Cameron of Britain and Prime Minister Ahmet Davutoglu of Turkey, were in Paris to attend the rally.

In a rare display of unity, the president of the Palestinian Authority, Mahmoud Abbas, and Prime Minister Benjamin Netanyahu of Israel also participated.

Security officials in France and across Europe remained on high alert for copycat attacks, even as a French prosecutor said that five people detained in the wake of the terrorist attacks had been released.

Early on Sunday, a German newspaper that had reprinted cartoons from the French weekly Charlie Hebdo lampooning the Prophet Muhammad was the target of an apparent arson attack, the newspaper reported on its website. It said there were no injuries.

The daily, the Hamburger Morgenpost, had published three cartoons that had been previously published by Charlie Hebdo, whose offices were attacked Wednesday in Paris. “This much freedom must be possible!” the headline read.

The Associated Press, citing police sources, said that the police in Germany had detained two men in connection with the Hamburger Morgenpost attack.

Several other national and local German newspapers published the cartoons and were placed under police protection, the news agency reported.

On Sunday morning, the French Interior Ministry held what it described as a security summit meeting, bringing together top intelligence and law enforcement officials from across Europe and North America to discuss ways to combat and contain terrorism. Attorney General Eric H. Holder Jr. was among those attending.

After the meeting, Bernard Cazeneuve, the French interior minister, said that the current European legislation aimed at fighting terrorism “wasn’t enough,” and called for a better European system for tracking potential jihadists and terrorists.

He also said the European ministers had agreed on a need for better cooperation with Internet companies to monitor, detect and remove any “illicit” material that could encourage terrorism.

Mr. Holder announced that the White House would convene an international forum on Feb. 18 to discuss new means of countering terrorism. The White House, in a statement, said the meeting would address domestic and international measures “to prevent violent extremists and their supporters from radicalizing, recruiting, or inspiring individuals or groups in the United States and abroad to commit acts of violence.”

The challenges raised by the attacks — including the threats of foreign fighters and the challenges of violent extremism — figured prominently at the meeting. On Saturday, French cabinet ministers held an emergency meeting in Paris to discuss measures to prevent other attacks.

The mass rally has created a major security headache for the French authorities, two days after security forces killed Amedy Coulibaly, a heavily armed gunman who is suspected of shooting and killing four hostages at a kosher supermarket near Porte de Vincennes in eastern Paris, and two brothers, Saïd and Chérif Kouachi, who are suspected of killing 12 people on Wednesday at the offices of Charlie Hebdo.

On Sunday, counterterrorist officials in France said they were continuing to investigate links between Mr. Coulibaly and the Kouachi brothers, the source of their funding and weapons, and whether the suspects were part of a dormant sleeper cell that had been activated.

The investigation is a challenge for French law enforcement officials, who are already grappling with the more than 1,000 French citizens who last year went or planned to join jihadists in Syria and Iraq. The events of the past week appear to confirm fears that some could return to wage attacks on French soil.

The attacks fanned anxieties across France and Europe and raised questions about why the authorities had failed to thwart an attack by suspects who were known to the French security services.

While the rally on Sunday was intended to help unite the country, it has fanned some divisions. Marine Le Pen, the leader of the far-right National Front, who was not invited, urged her followers to stay away, saying that the demonstration had been usurped for political ends “by parties which represent what the French hate: partisan spirit, electioneering and indecent polemic.”

On Saturday, hundreds of thousands of people marched in Paris, Toulouse, Nice and other cities in a show of solidarity, and rallies were held in places as far away as Athens, Madrid, Madagascar, Tel Aviv and Bangui, Central African Republic.

In Germany on Saturday, an estimated 35,000 people demonstrated in Dresden in support of tolerance and an open society, nearly double the number that attended the protests of a local group, Pegida, against what it called the “Islamization” of German society. Demonstrators on Saturday held a moment of silence for the victims of last week’s attacks in Paris, and many carried signs in support of the slain satirists from Charlie Hebdo.

In her weekly podcast, Ms. Merkel called for renewed efforts at unity among the European Union’s 28 members. “We are only strong and convincing when we stand together,” she said. Leaders of Germany’s Jewish and Muslim communities, backed by leading political parties, have called for Germans to attend rallies in support of tolerance on Monday in more than 20 cities across the country.

The rally in Paris on Sunday, which was to begin at 3 p.m. local time at the Place de la République, will be led by relatives of the victims of last week’s attacks.

The attacks have spread alarm among the Jewish community in France, which was already reeling from a spate of anti-Semitic attacks in the country, including on synagogues and Jewish shops last year, at the time of an Israeli incursion in Gaza. On Sunday, President François Hollande, who has labeled the attack at the kosher supermarket a horrific act of anti-Semitism, said he would meet with Jewish leaders at a rally after the main march.

In a meeting earlier on Sunday with Roger Cukierman, president of the Representative Council of Jewish Institutions in France, Mr. Hollande said that the government would protect Jewish schools and synagogues with army troops if necessary, and that it was committed to the security of France’s 500,000 Jews.

Mr. Hollande was expected to go to the Great Synagogue of Paris, also known as the Synagogue de la Victoire, after the unity march to convey his support for the Jewish community.

Thousands of Jews left France last year for Israel amid concerns about security, and in recent days Israeli officials have said that the recent attacks could prompt a new wave of French Jews arriving in the country. On Saturday, Mr. Netanyahu said that Israel was the home of French Jews, and on Sunday morning, as he was leaving Israel for the march in Paris, he repeated his invitation to French Jews to move to Israel.

“I am going to Paris in order to participate in the rally, along with world leaders, for a renewed struggle against the Islamic terrorism that is threatening all of humanity, which I have been calling for years,” the Israeli leader said.

Mr. Netanyahu said that he would attend a second rally, of Paris’s Jewish community, in the evening.

“I will say there that any Jew who wants to immigrate to Israel will be received here with open arms,” he said.

Mr. Netanyahu’s office announced on Twitter that the prime minister would bring the bodies of the Jewish victims of the kosher supermarket siege to Jerusalem for burial. The funerals are tentatively planned for Tuesday.

The French National Assembly is to hold a debate and vote on Tuesday on whether France should continue participating in American-led airstrikes in Iraq against the Islamic State.

France joined the campaign in September, and Islamic State militants have asked their supporters to attack Europeans in retaliation for the strikes. In September, a group aligned with the Islamic State beheaded Hervé Gourdel, a 55-year-old mountaineering guide from the French city of Nice, who had been kidnapped by fighters in Algeria.

New York Times | By DAN BILEFSKY and MAÏA de la BAUME