What lessons and conclusions can be drawn from the Brussels attacks?

I'm waiting for the Eurostar back to London wondering what lessons and conclusions should be drawn from this week's atrocities in Brussels. When I last made this journey, around a week ago, the Belgian authorities were patting themselves on the back after capturing Paris suspect Salah Abdeslam alive.

The week that followed has revealed the scale of the shortcomings in the way this country's government and security services have confronted it's huge problem with Islamist extremists.

If western military intervention is the main catalyst for such terrorism at home, why has tiny Brussels become a bigger incubator for extremism than any British or American city? After all, Belgium was hardly a major player in the wars that followed 9/11.

Of course, the foreign policies of countries like the UK and Belgium play a role in stirring the frustrations of some of its citizens. But the Belgian example has illustrated that it's what governments do at home - as well as abroad - that shape the breeding ground.

Some communities have been made to feel ostracised within a society that was already divided.

Too many Belgian Muslims say they are victims of frequent racism and islamophobia. The authorities have failed to stop it.

Undeniably, there's another problem here. Although politicians try to deny it, many public institutions are divided and dysfunctional. They are drawn apart by language - between French and Flemish-speaking departments - which breeds hostility, resentment and miscommunication.

This week, the chief of police in Mechelen, north of Brussels, admitted that his officers didn't share important intelligence about Salah Abdeslam which might have helped catch him months ago. His explanation seemed unsatisfactory. "Unfortunately a mistake has been made within my team... A colleague … forgot to pass on the information of the dossier.”

Other European countries have faced similar problems. But most have responded to the growing threat from terrorism by centralising institutions - doing more to ensure that the best people share knowledge and co-operate better, whichever department they work for. But perhaps that's not the Belgian way.

Compared to other European countries, Belgium has very few spies.For the security service here, a lack of officers and agents might have been a bigger problem than a lack of competence. It has around 600 staff. In contrast, there are thought to be 450 Belgians in Syria, and perhaps twice as many jihadists at home.

The Belgian government is trying to recruit more officers, but it might take two years to train them all.

It's difficult not to conclude that politicians here have failed to grasp the scale of the threat from domestic terrorism, even though it has been obvious for many years.