All Policy Analysis by Aaron Y. Zelin

As extremist foes fight for supremacy in Syria, their rivalries could threaten Europe.

Washington Institute research explains the complexities of the Islamic State in Iraq and al-Sham (ISIS).

While the long-term sustainability of the "Islamic State" is in doubt, Baghdadi has clearly steered the group back to prominence.

ISIS poses an existentially different threat than previous Sunni jihadist groups, with a focus on territorial possession and expansion.

Will the declaration of a new caliphate unite the world’s jihadists or tear them apart?

If history is any guide, the networks of fighters forged by the Syrian war will not remain silent in the coming years.

Aaron Y. Zelin examines the history and evolution of relations between ISIS and al-Qaeda, detailing factors that could help determine their respective agendas in the global Jihadi arena.

Why ISIS brags about its brutal sectarian murders in Iraq.

An expert on jihadist groups discusses whether ISIS will make more enemies than friends in Iraq as it continues its recent strategy of mixing violent repression with well-funded social work.

Who is ISIS, why has Iraq's army crumbled, and how can the United States help? Three experts discuss these and other issues during a Washington Institute Policy Forum.

The group's approach to other areas it has seized -- a mix of harsh repression and soft-power outreach -- offers insight into how it might consolidate control in Mosul.

The Mosul crisis highlights how ISIS has established a potent cadre of foreign jihadists who freely operate across the rapidly disappearing Iraq-Syria border.