Defense Secretary Ash Carter says the Pentagon is still not where it needs to be in its ability to detect insider threats to its computer networks, nearly two years after former National Security Agency systems administrator Edward Snowden leaked classified documents about government surveillance to reporters.

Carter was speaking to students at Stanford University, where he was unveiling the Pentagon's new cybersecurity strategy. In response to a question, he said the Snowden incident illustrates that the insider threat can be more dangerous than cyberthreats from outside antagonists.

He says the Defense Department has taken steps to better track what employees are doing online, detect suspicious behavior and prevent people from stealing data, but more needs to be done.