Testifying before the Senate Armed Services Committee last month, retired Gen. Keith Alexander, who recently stepped down as head of U.S. Cyber Command and director of the National Security Agency, expressed misgivings about America’s deterrent posture in cyberspace. In particular, he raised concerns about the lack of a threshold that, when crossed by cyberattackers, would prompt a U.S. response. According to Alexander, “The question is, when do we act? That’s a policy decision. . . . What we don’t want to do is let it get to the point where we find out, ‘OK, that was unacceptable,’ and we didn’t […]