Kings College London

A 2018 study by the International Centre for the Study of Radicalisation, at Kings College London, cited by the BBC, put the total number of foreign ISIS fighters at just under 41,500 from 81 countries, almost 6,000 of whom it says came from Western Europe.

A few weeks before Thursday’s attack in Barcelona, the Islamic State’s main online magazine posted an illustrated article with advice on acquiring a special kind of truck — specifically, the kind best suited for mowing down large numbers of pedestrians.

Turkey's contemporary history is notoriously complicated. Under each layer of the onion seems to lie yet another unforeseen set of intricacies. It is hardly surprising that many locals resort to spectacular conspiracy theories as mental shortcuts. 

'The New Turkey and its Discontents' by Simon A. Waldman and Emre Çalışkan (Hurst, £15, 344 pages)