"You need a spark and that spark has to be charismatic," Philip Mudd said. "... they could spark a revolutionary movement."
White supremacist groups are mentioned in the files, however they are described as a "medium threat."
"The U.S. government's failure to be at the table to discuss those policy approaches shows it doesn't take the fight against violence and terror online seriously," University of Sydney professor Fiona Martin said.
The material reportedly encouraged violent jihad against nonbelievers and urged the death penalty for women who have an affair.
During worship services, the religious group would play music and sing songs praising Islam's revered Prophet Mohammed.
Sunday marks 98 years since a 100-pound bomb turned the iconic street into a scene of bloody chaos.
Each anniversary of the 9/11 attacks prompts reflections on the war: Are Americans safer or did it go too far?
The assessment, from August, blamed "perceptions of police brutality" for violence against officers.
The device was packed with more than a kilogram of shrapnel.
Washington considers Abu Mohammed al-Jolani to be one of the world's most wanted extremists.
Counter-intelligence agency says there have been numerous incidents of bigotry and support of Hitler.
The group claimed responsibility for explosions that killed dozens of people in Homs.
Authorities detained relative of Cherif Kouachi in Turkey on his way to the war-torn country.
More patrols only deal with the symptoms, and not the root cause, of radical extremism, writes Kyle Orton.
Washington considers using Moscow's leverage to halt Assad's strikes against Syrian rebels.
The old-line extremist networks have no connection to today's "jihadist cool" aficionados.
Paul Refsdal embedded himself with Al-Qaeda's Nusra Front in Syria to detail their everyday lives.
Anti-assimilation group condemns Christmas event as attempt to steal Jewish souls.
Republican politicians now often echo conspiracy theories once relegated to troglodyte pamphlets.
An army chief spoke of over fears Islamic State recruits are using the army as a training ground.
The detainees are from London, Portsmouth, on England's south coast and from towns west of the British capital