ISIS-K Moscow attacks – who is at risk?

Islamic State, a group that once sought control over parts of Iraq and Syria, has claimed responsibility for Friday's mass shooting at a concert hall near Moscow that killed at least 139 people. U.S. officials have said they have intelligence indicating it was the Afghan branch, Islamic State Khorasan (ISIS-K), that was responsible. The Islamic State once sought control over swathes of Iraq and Syria, claimed responsibility for the attack.