At age 15, Shamima Begum left Britain to join the terrorist organization IS in Syria. She was one of several schoolgirls from London’s Bethnal Green neighborhood who went to marry IS fighters in 2015. The group’s online recruitment program lured many young people to its self-proclaimed caliphate. The extremist group is significantly weaker in the area now than it was at the time. Begum and many other British citizens who joined IS now want to return to Britain.