“Terrorist groups like al-Qaeda and ISIL deliberately target their propaganda in the hopes of reaching and brainwashing young Muslims, especially those who may be disillusioned or wrestling with their identity,” President Obama said last week in remarks wrapping up a Washington summit on Countering Violent Extremism. “The high-quality videos, the online magazines, the use of social media, terrorist Twitter accounts—it’s all designed to target today’s young people online, in cyberspace.”

The remarks reflected what's become something of a truism as the media routinely reports on ISIS’s “slick” propaganda apparatus, Western recruits becoming radicalized through social media, and the U.S. government's sluggishness—or outright ineptitude—in fighting back on the Internet. The State Department has a Center for Strategic Counterterrorism Communications with a team dedicated to countering "terrorist propaganda and misinformation about the United States across a wide variety of interactive digital environments," which, it admits on the department's website, "had previously been ceded to extremists." That office, as The New York Times recently reported, is slated for expansion. The online information war was a focus of last week’s summit.

But what if ISIS’s much-hyped social-media juggernaut isn't as important as all of these measures suggest?

“We know it has the potential to influence, but exactly how and at what levels are quite unknown,” Anthony Lemieux, an associate professor of communication at Georgia State University, wrote in an email. Lemieux is researching that very question, but in the meantime it’s difficult to find a reliable estimate of how many ISIS fighters have been radicalized and recruited primarily through social media. Max Abrahms, a political-science professor and terrorism specialist at Northeastern University, suspects the number is lower than many people believe. “There are other groups”—such as Boko Haram in Nigeria—“that have rapidly expanded their membership size in the absence of social media,” he pointed out to me. "Battlefield success is a better predictor" of group size than is social-media activity, Abrahms said. If, as some contend, ISIS's battlefield momentum has already stalled, its recruitment could suffer even as its social-media activity remains constant.

In tandem with its military successes, ISIS has also likely benefited from an influx of foreign fighters to Syria that predates the group's blitzkrieg in the summer of 2014. A record number of foreigners had already joined a variety of Syrian rebel groups by mid-2013, a full year before ISIS captured the Iraqi city of Mosul and began consolidating territory across the Syria-Iraq border. At the time, Thomas Hegghammer, a senior research fellow at the Norwegian Defence Research Establishment, acknowledged the role of social media in "the scale and speed of the mobilization." But, he continued, "this does not mean that social media in and of itself drives recruitment." Citing poorly policed borders and ease of travel to Syria, Hegghammer theorized: "The bottom line is that record numbers of foreign fighters are going to Syria because they can." Since then, ISIS's victories, among other factors, have enabled the organization to eclipse other rebel groups in terms of recruitment.

Western policymakers are quite reasonably preoccupied with ISIS’s recruitment of jihadists from Europe and the United States. But by far the biggest suppliers of the Islamic State's foreign fighters are Middle Eastern and North African countries, particularly Tunisia and Saudi Arabia, where broadband access lags behind access rates in the West. Among those who are online, according to a Soufan Group study of foreign fighters in Syria, potential recruits in the Levant and the Gulf "are interconnected within self-selected bubbles, and are isolated from anything outside." This implies both that social media helps ISIS amplify its message among closed groups that are already receptive to it, and that there are limits to how far that message can spread beyond those circles.

ISIS does have an enthusiastic base of supporters on English-language Twitter. But there’s a major difference between retweeting beheading videos or trolling the State Department and actually going to fight for the Islamic State. (For example, one vocal online propagandist for ISIS was revealed last December to be a corporate executive living in Bangalore, India.) According to official estimates cited in The New York Times, 150 people have “traveled, or tried to travel, to fight in Syria from the United States.” It’s not clear how many people actually succeeded in doing so. But it’s hard to imagine social media being the decisive factor in the decision to leave, say, suburban Colorado for Syrian battlefields, even if social media proved helpful in planning the trip. The causal relationship could just as easily work in the opposite direction: People engage with ISIS through social media because they’re already radicalized, rather than getting radicalized through social media.

Perhaps it’s the novelty of ISIS’s social-media operation, or its status as a major source of information about an otherwise largely opaque enemy and war zone, that make the group's tweets seem excessively threatening. The recent report that ISIS produces a large volume of social-media chatter—90,000 "tweets and other social media responses every day," by the Times's estimate, which may be conservative—doesn't actually say much about the role those communications play in terrorist recruitment.

As Brian Jenkins of the Rand Corporation noted in a 2011 study of "homegrown" extremists in the United States, reaching potential recruits online "does not mean radicalizing, and radicalizing does not mean recruitment to violent jihad." He also noted that while the Internet could "serve as a source of inspiration ... it may also become a substitute for action, allowing would-be terrorists to engage in vicarious terrorism while avoiding the risks of real action." Similarly, J.M. Berger, a Brookings analyst who studies extremists' use of social media, observed in 2011, "There is a tremendous amount of radical activity online. Very little of that activity will translate into real-world threats." Writing in The Atlantic, Berger also pointed out that even the volume of this activity may be less than meets the eye, since ISIS uses a number of techniques, including automated tweets and organized efforts to trend certain hashtags, to give the impression of a larger network of online support.

ISIS is surely a formidable force. Offline, the group is now estimated to be 30,000-strong or bigger. But the roots of its expansion probably don't lie on the virtual battlefield. More likely, they're on the real one.