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." Reason Science Correspondent Ronald Bailey reviews the data and finds that the Internet is actually not much help to terrorists in organizing transnational attacks. 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.