Someone is Testing Methods for Taking Down the Entire Internet by David Z. Morris @FortuneMagazine September 25, 2016, 12:23 PM EDT E-mail Tweet Facebook Linkedin Share icons Earlier this month, security expert Bruce Shneier revealed that companies responsible for the basic infrastructure of the Internet are experiencing an escalating series of coordinated attacks that appear designed to test the defenses of its most critical elements. He says that, based on the scale of the attacks, the most likely culprit is a large state cyberwarfare unit, with China at the top of the list of suspects. The ultimate goal of the efforts could include a “global blackout of all websites and e-mail addresses in the most common top-level domains.” Get Data Sheet, Fortune’s technology newsletter. Schneier, CTO of IBM’s Resilient and a fellow at Harvard’s Berkman Center, said that most of the attacks were standard, though huge, DDoS attacks —blasts of data designed to overwhelm servers. What distinguished them was their methodically escalating nature. The attacks, described by sources speaking to Schneier anonymously, are coming in slowly mounting waves, forcing companies to “demonstrate their defense capabilities for the attacker.” His inside findings align with a public report from domain registrar Verisign, which says that DDoS attacks have “continued to become more frequent, persistent, and complex.” There were also non-DDoS attacks, including attempts to tamper with Internet addresses and routing. For more on cybersecurity, watch our video. Schneier writes that this “doesn’t seem like something an activist, criminal, or researcher would do,” and that the scale of the probes suggests the involvement of a state. Though he doesn’t go into much detail, he says the “data I see suggests China, an assessment shared by the people I spoke with.” Also notable, as pointed out by Graham Templeton at ExtremeTech, is that both China and Russia have made significant strides in building systems that would resist any such mass takedown. Templeton also suggests that these tests were “meant to be seen,” for much the same reason that nations in the past have made their nuclear weapons and missile tests highly visible—as a means of flexing global power by demonstrating the ability to blow it all up.