By Vivienne Walt ~ PARIS 

A cell phone chimed in Brussels’ heavily Muslim district of Molenbeek after midnight on Nov. 14, as much of the world watched the carnage in Paris, where dozens lay dead in Europe’s worst terrorist attack in years. “Come get me,” read the frantic text message from Salah Abdeslam to two childhood friends in Molenbeek. “I’m in the sh-t.” He was right—the 26-year-old allegedly helped drive the killers to the attack sites, though police still do not know whether he joined in the shootings. As Europe reeled from the night’s horror, his two friends drove 300 km to Paris to collect Abdeslam. On the way back to Brussels they passed unimpeded through three French police roadblocks with one of the most wanted men in Europe in the backseat. He still hasn’t been found.

Of the 10 or 11 attackers that night in Paris, at least five came from Belgium, all but one of those from one small corner of Molenbeek, an area of 100,000 people just seven Metro stops from the E.U.’s headquarters. They include Abdelhamid Abaaoud, 28, the attackers’ ringleader, who lived steps from Abdeslam and whom neighbors remember as a boisterous kid with a loud laugh; Chakib Akrouh, 25, who Belgian officials believe massacred dozens of Parisians at sidewalk cafés during the attacks; and Abdeslam’s 31-year-old brother Brahim. Months after Akrouh and Abaaoud died in a fierce shootout with police in a Paris banlieue on Nov. 18, Belgian police uncovered their bomb factory in a townhouse just 4 km from Molenbeek. The crack jihadist commando force that emerged from these old cobbled streets was a product of ghettoization, poverty and years of political indifference that could take a generation to fix.

But Europe cannot wait that long. Intelligence officials warn that the Paris attacks, with 130 dead, could be only one part of deadlier atrocities ISIS has planned for Europe. Claude Moniquet, a longtime agent for France’s external intelligence service DGSE, who now runs a private intelligence company in Brussels, believes that ISIS will strike harder next time. “What we expect is a multi­city, multi­target attack at the same moment, and it will have terrible consequences.”

Officials believe between 470 and 520 Belgian citizens have traveled to Syria and Iraq to fight, most with ISIS. It’s a smaller total than in France or the U.K., but by far the biggest number per capita of any Western country. About 130 fighters are believed to have returned to Europe, including the Paris attackers—combat veterans, some with orders to strike Western targets.

Belgium has struggled with its identity since its modern establishment in 1830, a sliver of Europe where old schisms between French- and Dutch-speaking communities still linger, with the country split in two clear linguistic regions. Into this fragile mix came about 40,000 Moroccan migrants in the 1960s and ’70s to work in factories and coal mines, many building communities in gritty urban hubs like Molenbeek. Although analysts estimate Muslims constitute nearly 30% of the mostly French-speaking Brussels population, locals say many white Belgians regard even the third-generation citizens as outsiders. “These kids are born here. They eat hamburgers and listen to Beyoncé. But the society does not consider them Belgians,” says Bachir M’Rabet, 50, a coordinator for a youth center in Molenbeek.

ISIS can offer them a sense of belonging and purpose lacking in their local environment. “Jihadism is something where they can find themselves again,” says Alain Winants, who was chief of Belgium’s State Security ­Service, the main intelligence agency, and is now a Supreme Court prosecutor. “And they have what every terror group is dreaming of: Western passports they can travel freely on.”

But if marginalization and discrimination have created an ample supply of potential Belgian jihadists, as big a problem may be Belgian politics, splintered along geographic lines. Brussels, with 1.1 million people, has six separate police zones—none of which investigates terrorism. That is left to the federal police, who have struggled with lack of financing and staff. Days after the Charlie Hebdo attack in Paris in January 2015, Belgian federal police smashed a terrorist network in Verviers, near the German border, uncovering a major arms cache and an operational base in which one key player was Abaaoud. Yet the future leader of the Paris attacks had stayed out of sight.

There were other failures. Belgian police interrogated the Abdeslam brothers last year but couldn’t uncover their plans. They issued a warrant for another Molenbeek youth, 20-year-old Bilal Hadfi, after he left for Syria but then lost track of him—until Nov. 13, when he blew ­himself up outside Paris’ football stadium. “It’s like they were blind,” says Lars Bové, a Brussels reporter specializing in intelligence.

To Johan Berckmans, the longtime police commissioner in Molenbeek, the myopia was no surprise. Politics and a lack of resources have hamstrung local officials, he says. Molenbeek has just 110 police officers for the neighborhood where the Paris attackers lived, and the few Muslim officers on the force face hostility from residents. “If someone comes back from Syria, they should be followed,” Berckmans says. Yet he and Mayor Françoise Schepmans told TIME federal police had kept key information from them on as many as 85 suspects in Molenbeek, including who among them had previously fought in Syria and Iraq. “We did not have the means to prevent Nov. 13, or the means to avoid other attacks,” he says.

Frustrations run high at the federal level too. Winants, who was intelligence chief for more than seven years until 2014, says he grew exasperated trying to convince Belgian politicians that extremists were a threat to the homeland. A promised $217 million security budget in 2014 was canceled for lack of funds. Wiretapping was made legal only in 2010, and the security service is still restricted to monitoring suspects only while they are inside Belgium, a limitation that Winants fears might have helped Abaaoud and others plot the Paris attacks. “It is not possible for any intelligence service in the 21st century to remain internal,” he says. “We have no competence outside the territory.”

Belgian leaders admit failings but argue that the country has been unfairly blamed. “I don’t accept the criticisms aimed at denigrating the work of our security services,” Prime Minister Charles Michel told Parliament six days after the Paris attacks. Yet that day, Michel boosted policing and intelligence by $434 million—an eightfold increase—and proposed shutting down unregistered mosques, jailing or tightly surveilling returned foreign fighters and extending preventive detention from 24 to 72 hours. “We need to do more, and we need to do better,” he said.

Few know that better than those Belgians whose children have left to fight in Syria and Iraq. Véronique Loute and Géraldine Henneghien told TIME how their sons abandoned their comfortable lives to go fight in Syria. Loute’s son Sammy, 26, left for Syria in 2012 without telling her. He has telephoned a few times since but has not called her since August. Loute believes ISIS handlers are keeping him in Syria against his will.

Henneghien’s son Anis, 18, shocked his family by announcing in January 2014 that he wanted to “go help suffering Syrians.” She and her husband pleaded with Molenbeek police to ask the courts to revoke his passport. Without informing her, they decided it was not possible, since Anis was a legal adult. He soon left and was killed in Syria by a U.S. air strike last February. “If they had told me they would not stop him, I would have done something else,” Henneghien says.

After dozens of similar experiences, the parents of jihadists began meeting quietly in Molenbeek. “Eventually we decided we just had to get out and do something,” says Loute. Now about 20 parents, including those like Henneghien whose children have been killed, visit Belgian schools, describing to students their families’ devastation and urging them “not to listen to the peddlers of religion,” Loute says.

These grassroots efforts will need help from across the community. André Vandoren, a Brussels prosecutor who until last year headed Belgium’s Coordinating Unit for Threat Analysis, told a recent gathering that tackling extremism would require mosques, schools and prisons all to be involved. But this groundswell of attention comes too late for the families of the Paris attackers, many of whom still live in Molenbeek—or for the 130 people slain in Paris. Facing the anxious parents and teachers, Vandoren admitted he had few good answers to offer. “Let’s be clear,” he said. “All of us were surprised. All. So we need to change in a good direction.” Europe must hope that change happens before the next assault is launched.

Read this story on TIME Magazine.