Revenge strike? Evidence of a new cell and incompetent security services? A sign that the network of Salah Abdeslam, the man behind last year’s Paris attacks (arrested in Brussels on Friday after a failed joint counterterrorism operation with French police), is still active?

Three explosions erupted in Brussels. Both the airport and Maelbeek metro station were attacked, the latter during rush hour (up to 21 are reported dead). This attack proves that the threat of terrorist attacks do not disappear when a single figure within a terrorist organization is arrested. When Salah Abdeslam was captured, authorities said he was “worth his weight in gold.” His capture last week was considered a major blow to ISIS’s capabilities in Europe. Now he looks less significant.

This just proves how difficult the ongoing battle against contemporary terrorist threats is becoming. One week, the counterterrorism guys get one up and say they have dealt a major blow. The next, they look completely incapable of doing anything to counter the threat of terror attacks on their own soil. For the terrorists, their aim is to show they can still operate without their master (Salah), continuing to effectively pull off complex terror attacks despite the loss to their organization. This is not so much about revenge, but rather a simple demonstration of their continued capability, downplaying the effectiveness of the services trying to stop them. The battle is as much about propaganda battle.

Smoke was seen at Brussels Airport after explosions were heard. Belgium’s foreign minister, Didier Reynders, said on Sunday that Abdeslam had told investigators he was planning a fresh attack in the capital. “He was ready to restart something in Brussels, and it may be the reality because we have found a lot of weapons, heavy weapons, in the first investigations, and we have found a new network around him in Brussels,” Reynders said. That cell may have been able to carry out this attack before security services rolled it up.

It is possible the cell includes two other men suspected of playing major roles in the Paris attacks, and who have been on the run since November. Mohamed Abrini, 31, a Belgian of Moroccan origin, disappeared after allegedly playing a key part in the planning and logistics of the November attacks. He is a childhood friend of Abdeslam—their families used to be next-door neighbors in the Brussels neighborhood of Molenbeek, where several of the Paris attackers were from—and was described on his international arrest warrant four months ago as “dangerous and probably armed.”

Police are also hunting for a suspect known only as Soufiane Kayal. The man presented false papers in that name when he was checked at the Austria-Hungary border on September 9th. He was traveling with Abdeslam and Mohamed Belkaïd, a 35-year-old Algerian who was shot dead on Tuesday during a police raid in Brussels. The three men had posed as tourists heading to Vienna on holiday and did not raise suspicions.

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The cell will undoubtedly include many others. It is clear from the amount of time Abdeslam spent on the run that he was looked after by dozens of his contacts/friends/supporters. This is the reality of Islamic extremism in Europe. It is not about so-called lone wolves or solitary actors, but about a significant number of people who are deeply embedded in broader communities or neighborhoods.

“These people either share the attackers’ extremist views, or are at the very least prepared to support them out of friendship or family ties, or both. Studies have shown that a very high proportion of militant attackers talk to others in their close social circles, hinting at their plans.”

Others head to the police out of fear. A tip from within the community is believed to have led counterterrorism forces to Abdeslam last week, according to French media. One problem for our security services is that individuals who have only supported militants without acting violently themselves can easily and swiftly be turned into bombers/gunmen under certain circumstances, such as the detention of a key member or orders from more senior commanders.

They will do this out of fear or because they feel they are a part of the movement. Others just want to prove they have what it takes to be a jihadi. Over the past few decades, almost all attacks in Europe have involved local people attacking local targets with locally sourced materials and weapons. If the explosions on Tuesday morning in Brussels are indeed terrorist attacks, this is likely to be the case here, too.