"We know extremists are tweeting messages," he said. "They put out games, websites and magazines. This stuff is pretty slick. For someone who is vulnerable, they could get access to this and be inspired to do violence."
In a November article on the Brookings Institution website, analyst J.M. Berger noted that social media gives terrorists the advantage of volume.
By sifting through hashtags, posts and comments on Facebook, Twitter and YouTube, among others, organizations can seek out more potential recruits than ever before.
"The world continues to deal with the offline consequences of how ISIS works online, hunting among the fringes of society for those rare individuals who can be convinced to act on its behalf, wrote Berger, who studies U.S. relations with the Islamic World and wrote Jihad Joe: Americans Who Go to War in the Name of Islam.
The U.S. government and social networks have taken steps to not only pull terrorist groups off the social networks but to use social sites to supplant their violent messages.
For instance, in February, Twitter announced that it was accelerating its efforts against terrorist groups, increasing its team that reviews reports of Twitter accounts associated with violent extremism and suspending 125,000 accounts for threatening or promoting terrorist acts since the middle of 2015.
Twitter also said it was working with law enforcement on the issue.
Facebook also has suspended accounts that it finds are associated with radicalized groups.
In February, Facebook co-founder and CEO Mark Zuckerberg said at the Mobile World Congress in Barcelona that he wanted to stop terrorist groups from celebrating attacks on Facebook and to keep them from using the social network to lure in and train new recruits.
The fact that both Twitter and Facebook have been working to stop terrorists from using their networks has not been lost on ISIS. In February, ISIS made direct – and violent - threats against the CEOs of both companies.
In a video posted to Telegram titled "Flames of the Supporters," the Sons Caliphate Army, the hactivist arm of ISIS, showed photos of Zuckerberg and Twitter CEO Jack Dorsey with digitally added bullet holes.
"You announce daily that you suspend many of our accounts, and to you we say: Is that all you can do?" the hackers wrote in text across the video. "You are not in our league.... If you close one account we will take 10 in return and soon your names will be erased after we delete your sites, Allah willing, and [you] will know that we say is true."
Facebook, Twitter and Google did not respond to repeated requests for comment on terrorists' using of their sites.
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