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The IS group - specifically Islamic State Khorasan - has claimed responsibility for the worst terrorist attack to hit Russia in 20 years.
Eight suspects have now been remanded in pre-trial detention over the concert hall attack that resulted in 139 deaths.
Analyst David Sedney was a former US deputy assistant secretary of defense for Afghanistan, Pakistan and Central Asia.
He told Rayane Tamer that the ISK group is a part of a broad, multi-continental movement that needs to be countered.
