The details of what happened after the two bombings in Brussels on Tuesday morning are now well known, and the Islamic State (also known as ISIS, ISIL, or Daesh) has claimed responsibility for the attacks. Three of the perpetrators have been identified and some background information is beginning to emerge, but it is still far too soon to know everyone involved in the planning and execution of these attacks. It is already clear, however, that this week's events in Belgium were likely intimately associated with last November's attacks in Paris.
Just before 8 a.m. Ibrahim El Bakraoui and two other men arrived at Zaventem airport by taxi. They each placed a suitcase containing a bomb on a luggage trolley, and then entered the departure hall together. An explosion occurred soon after in front of the American Airlines check-in desks, and seconds later another device was detonated beside a Starbucks café. A third device failed to explode and was detonated later in a controlled explosion.
An hour after the attack at the airport, Ibrahim's brother Khalid El Bakraoui attacked a train leaving the Maelbeek metro station in central Brussels, not far from the European Union's offices. The targets in Brussels were clearly chosen to maximize casualties and the psychological impact of the attacks, and to create significant disruptions of transit infrastructure resulting in substantial economic damage. More than 260 people were wounded in the two attacks and 33 are known to have died.
The taxi driver who drove the three men to the airport was able to lead police to the address in the northern Brussels suburb of Schaerbeek where he had picked them up. An explosive device containing nails, "chemical products," and an ISIS flag was discovered when the apartment was raided that evening. The explosive found was reportedly triacetone triperoxide (TATP), the same one used in the attacks in Paris in November 2015. While the materials to make TATP are not hard to acquire, the highly unstable nature of the materials suggests this operation, too, was guided by individuals possessing substantial explosive expertise.
On Friday March 18, four days before the Brussels bombings, Belgian authorities arrested Salah Abdeslam, the main surviving suspect in the assaults in and around Paris last November and described as the most wanted man in Europe. Abdeslam was arrested in Molenbeek, where he and three of the Paris attackers, including ringleader Abdelhamid Abaaoud, grew up. Molenbeek is a predominantly Muslim area with high levels of unemployment and social exclusion, coupled with a long-time and well-established presence of Salafist thought—a combination seen as an important contributing factor in the radicalization of members of the local community.
The Paris attacks revealed that their perpetrators could rely on a strong support network in Brussels, and Abdeslam may have been hiding in Molenbeek since these attacks were executed last November. Following his arrest it was reported that he was planning more attacks. Because striking multiple targets with suicide bombers requires considerable preparation, Tuesday's attacks were likely planned before Abdeslam's arrest last week. It is probably no coincidence that the attacks occurred just four days after the arrest; it is possible that, suspecting the authorities of closing in upon them, the Brussels bombers may have expedited the execution of their plans.
Verisk Maplecroft, a sister company of AIR Worldwide and a Verisk Analytics business, contributed to this post.