It has been described as "one of the most dangerous terrorist groups" in history. The rise of the Islamic State of Iraq and the Levant (ISIL), which has seized large areas in Syria and Iraq and was reportedly responsible for more than 50 attacks, killing almost 1,000 civilians in 2015, has mobilised world powers to vow to destroy it. But as ISIL attacks continue to strike fear throughout the world, what motivates the group; what is its end game; and how can it be defeated?

In this special edition of UpFront, we speak to four of the world's leading authorities on ISIL who have interviewed the group's members and extensively studied its actions. Mehdi Hasan also challenges the common view that ISIL and al-Qaeda attackers are devout Muslims.

Guests:

Lydia Wilson, research fellow at Oxford University's Centre for the Resolution of Intractable Conflict, and recently granted permission to interview ISIL fighters imprisoned in northern Iraq.

Will McCants, senior fellow in the Center for Middle East Policy at the Brookings Institution, a former State Department senior adviser on countering violent extremism, and author of The ISIS Apocalypse.

Hassan Hassan, a fellow at the Tahrir Institute for Middle East Policy and Chatham House and co-author of ISIS: Inside the Army of Terror.

Jurgen Todenhofer, described as "the first Western journalist" to be granted access to ISIL-controlled territory, and author of the book Inside IS: 10 Days In The 'Islamic State'.

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Source: Al Jazeera