A photo tweeted by the jihadist group Welayat Salahadden, allegedly showing Islamic State gunmen executing Iraqi soldiers in civilian clothes north of Baghdad. Social media has been a big recruiting tool for the Islamic State. (Welayat Salahadden/European Pressphoto Agency)

Daniel Byman is a professor in Georgetown University’s School of Foreign Service and the research director of the Center for Middle East Policy at the Brookings Institution. Jeremy Shapiro is a fellow in the Brookings foreign policy program. This piece draws on their work on foreign fighters in Syria that will appear in the forthcoming issue of Foreign Affairs.

The Islamic State mixes primitive savagery and high-tech sophistication. Its fighters behead and crucify while they post photos of a child holding a severed head and tweet about cats. Although the content is abhorrent and helps the Islamic State radicalize and recruit in the West, the group’s massive social media presence is also useful to those fighting terrorism.

The Islamic State’s public relations campaigns are slick, even hijacking seemingly benign hashtags such as #WorldCup2014 to propagate the militants’ message. And the propaganda is issued in multiple languages — including English, French, Russian and Turkish — to appeal to potential followers. Some of this content is spread from the top ranks of the Islamic State, but the jihadists also have thousands of online followers who retweet messages and create their own content, enabling them to effectively crowdsource jihad.

Although such death videos nauseate most of the world, they make the Islamic State look cool to a key demographic: angry young Muslim men susceptible to indoctrination. Throw in a bit of sectarian hatred and a touch of promise about Islamic government, and the mix helps keep the Islamic State well supplied with impressionable foreign fighters.

On the other hand, the Islamic State’s broadcasting of its brutality over social media makes it easier for people to support the United States and its allies’ war with the militants, and it has sparked calls to block the jihadists from the Internet. In the United States, sites such as Facebook, Twitter and YouTube remove some offensive comments linked to terrorism, with support from government agencies. British Prime Minister David Cameron has gone one step further, saying the time has come to be “intolerant of intolerance” and boasting of government efforts to take down thousands of Internet pages.

How can democratic governments, with great concern for civil liberties and free speech, ever hope to impose their will on social media? In some cases, banning particular sites or individuals may make sense if the risk of recruitment and radicalization is high. But those risks have to be weighed against the intelligence value of having groups such as the Islamic State active on social media.

Social media is a counterintelligence nightmare for Islamic State militants. Although tweets and Facebook postings inspired them to fight and helped them get to Syria and Iraq, these technologies are easily monitored. As former FBI official Clint Watts points out, social media offers “a window into what’s going on in Iraq and Syria right now.” The same bragging the group did in Syria to inspire others can be turned against it: Intelligence services can determine the identities of supporters and potential recruits, flagging individuals not previously on the government’s radar.

With data analysis, governments can use social media to trace entire networks of contacts. A constant problem for intelligence services is detecting a terrorist before he acts. Now we have one good marker: The would-be terrorist is a “friend” or a “follower” of militants in Syria. The Carter Center, among many other organizations, has used online data to map the complex Syrian civil war with a level of fidelity that was never possible in previous conflicts. Intelligence agencies are putting it to similar good use.

At the very least, intelligence officers can learn the most prominent ways jihadists recruit others and try to counter them. At best, they can communicate with actual and potential terrorists, feeding information — and misinformation — to their networks.

Like political movements everywhere, terrorists have a message they want to communicate. But because every fighter can broadcast anything to the world, leaders cannot control the narrative. For example, the Islamic State is in a flame war with Jabhat al-Nusra, the official al-Qaeda affiliate in Syria: The contest makes both groups less appealing as it reveals divisions within the jihadist camp for all to see. According to European security officials we interviewed, this dissension turns off potential recruits.

If foreign fighters return home, they might find that they have incriminated themselves on social media. In most Western countries it is illegal to join a designated terrorist group such as the Islamic State, but in the past it was often hard to prove that someone was a member of such a group. Tweets and Facebook pictures of fighters standing over dead bodies and declaring their allegiance to Islamic State leader Abu Bakr al-Baghdadi don’t look good in a court of law.

Because the volunteers think they are heroes joining an army, they are not operating in a clandestine way. Despite Edward Snowden’s leaks and other revelations about the power of the National Security Agency, terrorists seem to think that no one is listening — or that they don’t care. As John Mueller, a senior fellow at the Cato Institute, told us, “We’ve had 13 years in which officials talk about how they listen to ‘chatter’ by jihadists, and yet the jihadists continue to chatter.”

Beyond the debate about the wisdom of barring terrorists from social media, it may simply be impossible. Web sites and Twitter accounts move and reappear as quickly as they can be taken down. Technological tools and methods quickly arise to circumvent controls — and those who most want to avoid scrutiny are the first to go underground. Even the Chinese government, with all of its vast apparatus and effort devoted to the Great Firewall of China, has not succeeded in completely cutting off protesters from using social media.

In most cases, social media promotes openness, collaboration, creativity and the spread of information. But when it comes to terrorism, social media is both disease and cure. It has helped the Islamic State recruit and grow, but it also strengthens the counterterrorism response and ultimately will weaken the group’s message. Even though terrorists can exploit social media, these networks are an important source of our strength and our advantage over repressive groups such as the Islamic State.



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