BRUSSELS — There are military trucks parked in Molenbeek, and soldiers with submachine guns patrol the jittery streets of the Brussels district that has been the epicenter of European terrorism in recent months. On the Place Communale idle youths loiter, shooting glances at the police. This is where the Paris and Brussels attacks, with their 162 dead, overlap.

Salah Abdeslam, the only surviving direct participant in the Paris attacks, hid in Molenbeek before his arrest on March 18. Abdelhamid Abaaoud, the suspected chief planner of the Paris attacks, lived in Molenbeek. In all, at least 14 people tied to both attacks were either Belgian or lived in Brussels.

One of them is Mohamed Abrini, a Belgian of Moroccan origin who grew up in Molenbeek and was arrested in Brussels on Friday. He has told the police he is “the man in the hat” caught on surveillance cameras leaving Brussels airport after two accomplices blew themselves up on March 22. Cameras also placed him in Paris last November with the Paris attackers.

Sleepy Brussels: goodbye to that image. Yet even today there’s something soporific about this French-speaking city marooned within Flemish-speaking Flanders, beset by administrative and linguistic divisions and the lethargy that stems from them, home to a poorly integrated immigrant population of mainly Moroccan and Turkish descent (41 percent of the population of Molenbeek is Muslim), and housing the major institutions of a fraying European Union.