Extremists belonging to so-called Islamic State have lost a number of towns and cities recently, including Palmyra. But does that mean that they are being beaten?

One man with an insight into that question is the German author, politician and former judge, Jurgen Todenhofer.

He has written a book called My Journey into the Heart of Terror after spending 10 days living with IS in Syria and Iraq, and spoke to the BBC's Yalda Hakim.