We are dangerously dependent on Internet-based systems. All these incidents threatened the social fabric of the victimized societies. If the Russians hacked the Democrats, who might be next? Could whoever triggered Dallas’s sirens turn off the traffic lights or the local power grid? How safe are electronic financial transfers?

Ransomware validates these fears. What was stunning is how quickly the recent outbreak spread. One estimate had it quickly migrating to 150 countries and affecting 200,000 computers. Despite the rapid response — the discovery of a so-called “kill switch” in the malware that deactivated the virus — the basic message remains: Much health care, transportation and ordinary business might close if deprived of Internet access, whether by hostile governments (North Korea?) or cybercriminals.

This makes the Internet a weapon that can be used against us — or by us. In a presentation to the Senate Intelligence Committee, Daniel Coats, the director of national intelligence, put it this way: “Our adversaries are becoming more adept at using cyberspace to threaten our interests and advance their own, and despite improving cyber defenses, nearly all information, communication networks and systems will be at risk for years.”