Depending on your point of view, U.S. General Keith Alexander is either an Army four-star trying to stave off a cyber Pearl Harbor attack, or an overreaching spy chief who wants to eavesdrop on the private emails of every American.
Alexander, 61, has headed the National Security Agency since 2005, making him the longest-serving chief in the history of an intelligence unit so secretive that it was dubbed "No Such Agency." Alexander also runs U.S. Cyber Command, which he helped to create in 2010 to oversee the country's offensive and defensive operations in cyberspace.
The dual role means Alexander has more knowledge about cyber threats than any other U.S. official, since the NSA already protects the most sensitive U.S. data, extracts intelligence from foreign networks and uses wiretaps to track suspected terrorists. But it also puts the general at the center of an intense debate over how much power the government should have to spy on private citizens in the name of protecting national security.
"He's lasted as long as he has because he's focused and he's persistent. I've never heard him yell," said retired four-star general Michael Hayden, who was Alexander's predecessor at the NSA. "He doesn't spread himself too thin. He decides what's important and puts his personal energy into those things."