Alexander says U.S. networks under constant attack

"Our DOD must be able to operate freely and defend its resources in cyberspace," Alexander said. "We will do this as we do it in the traditional military domains of land, sea, air and space."

Some critics have contended that Alexander's role as a top intelligence official makes him a poor choice for the top cybersecurity post, but he countered that the connection would greatly benefit the new command. Alexander said the NSA's resources and personnel would be critical to the success of CyberCom.

"Technology is part of the solution, of course, but the key is people," Alexander said.