At least 28,000 Twitter accounts supporting the Islamic State of Iraq and al-Sham (ISIS) have been set up since the beheading of American journalist James Foley, according to a Web intelligence firm. Twitter vowed to suspend accounts posting graphic imagery or "calls to violent actions" after Foley's murder was filmed by the Sunni group and then spread online last month. But an analysis by Recorded Future that carried out for Britain's Sky News showed 60,000 pro-jihadi profiles had been set up since May, including 28,000 since the video of Foley’s murder emerged on August 20.

And in the 24 hours after video was released showing U.S. reporter Steven Sotloff’s murder by ISIS, 10 percent of all references to the footage were positive, the analysis showed. ISIS has employed Twitter, sophisticated videos and professional-sounding music recordings to spread its message around the world in a way not seen before in militant organizations.

In-Depth

- Alexander Smith