ISIS - otherwise known as ISIL or Daesh - rose to prominence in 2013-14 after they became a significant force in the Syrian civil war, and began launching several successful offensives against Iraqi security forces. By the end of 2015, ISIS controlled territory stretching from western Iraq to eastern Syria. They gained notoriety for imposing an incredibly brutal interpretation of Sharia Law on the people under its control, which was estimated to be between eight and twelve million people.

The creation of an Islamic Caliphate threatened stability in the Middle East unlike anything that came before it, whilst its unprecedented use of social media established ISIS as the leading jihadist group world wide. But was the emergence of ISIS as a regional and global threat a strategic surprise? Dr Aviva Guttmann (Aberystwyth University) is on the show today to talk about the factors behind this success. Dr Guttmann is a specialist in counter terrorism studies and has recently written an article in which she describes the rise of ISIS as a 'partial surprise'. So we'll be asking Aviva what was surprising about ISIS, and why was it difficult for analysts to fully predict?