The rise of the Islamic State group has been both shocking and unprecedented. With ever more violent attacks on civilian targets come outpourings of anger and frustration at the inability of governments and security services to defeat them. The aftermath of the Paris attacks has been no exception. President Hollande has spoken of waging a “pitiless war” against those responsible. Amid the atrocities committed by IS, it’s difficult to perceive a coherent ideology. So in this week’s Newshour Extra, Owen Bennett Jones and his guests discuss where the group came from, what its leaders want, and whether it’s succeeding in its aims. In understanding such motivations, are we better equipped to defeat it?

This week's contributors: Jason Burke - Guardian newspaper and author of "The New Threat from Islamic Militancy"; Jessica Stern - Harvard lecturer and the co-author of "ISIS: The State of Terror"; Hassan Hassan - Chatham House and co-author of "ISIS: Inside the Army of Terror"; Ghias Aljundi -Syrian writer and human rights activist.

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