Brussels attack: were they revenge for Abdeslam's arrest?

The causes of the attacks are still unfolding but previous outrages show that terrorists often strike close to home Brussels explosions: multiple casualties after airport and metro blasts - live Revenge strike? Evidence of a new cell and incompetent security services? A sign that the network of Salah Abdeslam, the logistician for last year's Paris attacks who was arrested in Brussels on Friday, is still functioning? Or - given that we still have very few details of Tuesday morning's events - non...