I'm not sure who did it, but it's not wrong to say we should have controls at the border and screening of migrants. That is like national security 101. It also seems that Belgium is lacking in terms of intelligence against possible threats as well, unlike the Germans who seemingly have sniffed out possible attacks a few times now.
If these were home-grown Belgians upset over racism, lack of opportunities, et cetera, you’re not going to solve that by improving their conditions either since they are attached to their radical ideology. Of course you can and should attempt to make things better, but you’ll still have to manage the threat. To me, that shouldn’t mean making everyone else’s lives more painful just to accommodate certain folks. That’s why you need targeted intelligence instead of broad police state measures like we see in the US, all of which I abhor.