Terrorists are using the Internet to plot "murder and mayhem," British Prime Minister David Cameron declared this week, as a parliamentary committee issued a report accusing Internet firms of providing a "safe haven for terrorists." Cameron and the committee were referring specifically to a brutal knife attack that killed British soldier Lee Rigby on a London street in May 2013, but the charge has been levied more broadly as well. Earlier this month, British spymaster Robert Hannigan claimed that Silicon Valley had created "the command-and-control networks of choice for terrorists." In October, Spanish Secretary of State for Security Francisco Martinez warned that the ruthless ISIS terrorist group now dominating swathes of Syria and Iraq regards the Internet as "an extension of the battlefield," adding that they might be using it to organize an attack in the West using the Ebola virus.

Fortunately, there's good reason to believe these officials wrong. David Benson, a political scientist at the University of Chicago, argues in the summer issue of Security Studies that there is very little evidence that the Internet is making terrorism easier to do. While "access to the Internet has increased across the globe," he writes, "there has been no corresponding increase in completed transnational terrorist attacks."

Benson defines terrorism as "violence by non-state actors intended to terrorize or frighten a target audience." He focuses on transnational terrorism because the fear of attacks across international borders drives major changes in policy.

The Internet might benefit would-be transnational terrorists by offering anonymity, access to information, and cheap communication, which in turn increases both their capabilities and their ability to network. Anonymity blunts attempts to preempt attacks; information about how to build bombs and carry out attacks is widely available; and cheap communication makes long-distance coordination possible. In theory, all this should make it easier to carry out attacks in other lands.

But as Benson points out, analysts err when they assume that "transnational terrorists have a similar base of support as nationalist or local terror organizations." Local terrorists live among people from whom they can seek support and recruits. They can assess targets in person, and they can meet to research, plan, and prepare using local channels to communicate. Transnational terrorists, by contrast, cannot rely on local support for either recruits or operations.

Benson adds that terrorists are not really all that anonymous, since Internet activity leaves tracks that sophisticated sleuths can follow, and that the availability of bomb-building schematics is no substitute for actual weapons-making experience. Furthermore, governments and other outside groups are adept at monitoring terrorists' communications.

Benson thinks most analysts inflate the Internet's importance because they reason backwards: They look at individual attacks, then assess how the terrorists used the Internet to realize their plans. "Since the Internet is ubiquitous, it would be strange if today's terrorists did not use the Internet, just as it would have been strange if past terrorists did not use the postal service or telephones," Benson notes. The key issue is whether transnational terrorist attacks are increasing with the spread of the Internet.

The activities of Al Qaeda have been a focal point for public anxieties, so Benson lists the atrocities committed by Al Qaeda between 1995 and 2011. Using the number of casualties as the benchmark for assessing capabilities, Benson observes that there is a steep reduction in the number of people killed and wounded by Al Qaeda operatives after the attacks on the U.S. embassies in Kenya and Tanzania on August 8, 1998, and the September 11, 2001, barbarity. Benson argues that most of this fall off in effectiveness came as a result of losing their safe havens in Sudan and Afghanistan. Communication and instruction over the Internet is no substitute for face-to-face talk and hands-on training.

After 9/11, various local terrorists groups found value in the Al Qaeda brand and offered to become franchise operations. These franchises include Al-Shabaab in Somalia, Al Qaeda in the Arabian Peninsula (AQAP), and Al Qaeda in the Islamic Magreb (AQIM). Benson excludes Al Qaeda in Iraq and Jemaah Islamiyyah in Indonesia because their operations are almost entirely local. The others are largely local too, and when they do carry out an attack in another country it is usually in a neighboring nation. All of the "transnational" attacks done by the Algeria-based AQIM, for example, have occurred next door—in Morocco, Mauritania, Niger, Mali, and Tunisia.

Some of those countries are practically Internet-free zones. Usage rates in Mali and Niger, for example, are under three percent. Similarly, Internet penetration in Somalia, where Al Shabaab operates, is about 1.5 percent. Attacks are organized by local terrorists who meet and train together face-to-face. "Almost all of [Al Qaeda's] successful attacks following 2005 were completed by local terrorist organizations," Benson observes.

The 2014 Global Terrorism Index notes that 2013 was "the peak year in global terrorist activity not only in the early 21st century, but also for the entire period since 1970," when the statistics in the Index first begin. Deaths from terrorism increased 61 percent, rising from 11,133 in 2012 to 17,958 in 2013. But despite this dismaying increase, "The bulk of terrorist activity in the world is accounted for by militant actors that pursue relatively limited goals in local or regional contexts." Eighty-two percent of the fatalities caused by terrorism in 2013 occurred in just five countries: Iraq, Afghanistan, Pakistan, Nigeria, and Syria. (Internet penetration in those countries is 7.8 percent, 6 percent, 11 percent, 38 percent, and 27 percent, respectively. By contrast, about 87 percent of Americans have access to the Internet.)

The Index further observes that 66 percent of the claimed deaths from terrorism in 2013 are claimed by only four terrorist organizations: ISIL, Boko Haram, the Taliban, and Al Qaeda and its affiliates. Since 2000, only 5 percent of all 107,000 fatalities stemming from terrorist attacks have occurred in OECD countries—and that includes the 2,996 who died on 9/11.

In an article last year for the Journal of Peace Research, the University of Texas at Dallas* economist Todd Sandler reports that transnational terrorist attacks rose from 1968 until the mid-1980s, largely as a result of increasing state sponsorship. During the 1990s, the "number of transnational terrorist incidents fell precipitously." While the number of transnational attacks has dropped, the percentage that result in casualties has risen to about 50 percent today, up from about 20 percent in the mid-1990s.

Meanwhile, the same Internet used by terrorists is used by governments to gather intelligence. And as terrorists recruit online, friends and family members use social media to engage and intervene with people at risk of radicalization. So it's not as though all the Internets effects run the same way.

And often what initially looks like a transnational attack might turn out to be local after all. Consider that parliamentary report on Lee Rigby's murder. The attack was carried out by two British nationals, Michael Adebolajo and Michael Adebowale, of Nigerian heritage. The report notes that Adebowale expressed his desire to kill a British soldier in a single Facebook chat with an extremist thought to be associated with AQAP. But it adds that the British intelligence agency MI5 "told the Committee that they believe that, while Adebowale and Adebolajo were in contact with other extremists, they planned the murder of Fusilier Lee Rigby without external support, tasking or direction." In other words, the attack was a local action planned locally by local actors, not a transnational plot organized over the Internet.

As Benson argues, exaggerating the Internet's usefulness to terrorism has "egregious costs." Some officials, for example, have been calling for a "kill switch" that would allow the government to shut down the Internet in an emergency. Noting how much Americans depend upon the Net for commerce, communication, medical care, and so forth, Benson points out that "It is difficult to imagine a terrorist attack being as costly as turning off the Internet would be."

But casting the Internet as a "safe haven for terrorists" does give governments another excuse to violate our privacy in the pretense of protecting our security.

*Correction: In the original version, I erroneously stated that Sandler was at the University of Dallas.