The US director of national intelligence says ISIL remains a threat despite its recent defeats in Syria and Iraq.
Dan Coats told a gathering of world leaders, diplomats and defence officials at the Munich Security Conference on Saturday that defeating the extremist group was like "killing an octopus".
He said: "It's more than just a terrorist organisation. It is an ideology and perhaps a theology, and the combination of ideology and theology outlasts defeats on the battlefield."
The director admitted it was not currently clear whether "we've done enough to keep ISIS from reconstituting, or if we're just in a moment of pause while they're regrouping".
Mr Coats said the current assessment is it "will remain a threat".
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