The Threat of ISIS to the UK: RUSI Threat Assessment

The Islamic State of Iraq and Syria (ISIS) is well financed, well equipped and brutal. It is also a plausible threat to the UK.

Download the briefing here (PDF)

The group operates across large swathes of territory in Syria and Iraq, where the sustained conflicts continue to attract large numbers of foreign fighters. Official estimates suggest the total travelling to the region has now exceeded 15,000, including 500 from the UK. It is unclear what proportion has joined ISIS, though it is understood that a majority of these UK citizens have joined its ranks. This briefing argues that it is this community of foreign fighters that poses an immediate terrorist threat to the West.

As the UK joins the coalition against this increasingly dominant jihadist force, understanding the scale of the threat and the complexity of the challenge is crucial. This briefing analyses four key questions: 

What is the group’s current narrative and interest? 

How is this narrative being heard in the UK? 

What would change to make ISIS refocus from its regional concentration

to a global one? 

How might a new ‘awakening’ movement be stimulated in Iraq? 

This briefing provides an objective view on ISIS and some judgements about its current threat trajectory. It draws on a series of discussions held at RUSI, which involved internal and external expertise, to come to some key judgements on the group.