Despite the emergence of story after story about politically charged email hacks, corporate-security breaches, and secret drone strikes, we still think of the perpetrators as bad actors. Yet as Yasha Levine shows in this bracing book, the truth is simpler. The internet was built to be a weapon, and it's been getting ever more effective.

Since ARPA began building it in the 1960s, internet technology has been synonymous with spying. Levine traces this history, starting with the visionary scientist William Godel, who realized that the key to winning the war in Vietnam was not outgunning the enemy but using new technology to understand and anticipate their movements. As the book spins forward in time, Levine shows that many of the tech-industry giants we think of as social networks, e-tailers, and search companies are doing double duty as military contractors and security outfits.

Levine is unafraid to name names: Google, IBM, Facebook, and many others make...