It is still unclear exactly what Brussels has faced just prior to Easter. The random nature of the date and targeting suggests a plot that may have been brought forward, while the scale of the attack suggests it must have been in the pipeline for some time. The Isis network, also linked to November’s Paris attacks, has claimed responsibility. The bigger issue, however, is not who is to blame for this atrocity but rather how much Europe will warp to address an acute terrorist threat, with cells apparently able to launch large-scale atrocities on an increasingly regular basis.

The first questions raised will focus on Belgium’s response to the problem on their home ground. Authorities may have scored a victory by capturing Salah Abdeslam, one of the Isis-aligned plotters linked to the Paris attacks, but they missed a network planning an atrocity with heavy weapons and explosives. This suggests gaps in the understanding and surveillance of the terrorist threat. Given that Brussels sits at the political heart of Europe, this points to a problem that can no longer be described as Belgian alone.

While for some the terrorist atrocities in Paris was a wake-up call, for security forces it had been expected for a while. Terrorist groups, from al-Qaeda to Isis, have long sought to launch a terrorist attack in the style of the 2008 Mumbai attacks, and a string of plots have been disrupted or launched from a francophone network emanating from Brussels. The Paris attack was the realisation of these fears from a depressingly predictable place.