A playground is seen in London, outside an address where Kuwaiti-born London computer programmer Mohammed Emwazi is believed to have lived. Emwazi has been identified as masked ISIS militant "Jihadi John." Niklas Halle'n/AFP/Getty Images hide caption

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Somali-American youths play basketball before the start of a September 2013 solidarity rally by the Minneapolis Somali community to denounce al-Shabab's attack of a shopping mall in Nairobi, Kenya. Less than a decade after groups of teens from Minneapolis emigrated to Somalia to join the terrorist group, more have been recruited to join the self-declared Islamic State in Syria. Eric Miller/Reuters/Landov hide caption

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Cherif Kouachi, one of the brothers responsible for the Charlie Hebdo attacks, spent 20 months in Fleury-Merogis prison just outside Paris, where he crossed paths with a radical imam with ties to Osama bin Laden.This photo shows the men's building in May 2014. Charles Platiau/Reuters/Landov hide caption

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Police officers look for an escaped suspect Jan. 9 in Porte de Vincennes in Paris, France. Hayat Boumeddiene, 26, escaped and is wanted in connection with the murder of a policewoman. Aurelien Meunier/Getty Images hide caption

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