If you want an idea of what "cyber warfare" means to the US Navy, check out this short video about the Tenth Fleet, home to the Navy's cyber warriors.
It's a bit melodramatic--though not so bad on production values. But it tells you how the Navy sees its role in the "fifth domain" of combat; protecting networks, stopping attacks, and, when necessary, pairing cyber offense with "kinetic" military force.
"Cyberspace is where the battles of the future will be won or lost," says the film's narrator. It's a hotly debated point, of course. But if you want a window into why the Navy--or at least the Tenth Fleet--believes this is true, have a look.