By Phil Stewart in Aspen, CO, Reuters, July 18, 2013

[....] Deputy Defense Secretary Ashton Carter told a security forum that the government was already moving to better isolate intelligence so that all of it isn't accessible in one place, and to implement a "two-man rule" - similar to procedures used to safeguard nuclear weapons.

"When are we taking countermeasures? ... The answer is now," Carter told the Aspen Security Forum in Colorado. "This failure originated from two practices that we need to reverse."

U.S. intelligence agencies conducting a forensic review of the activities of Snowden, a former National Security Agency contractor, are close to pinning down the extent of the classified documents he accessed and the means by which he removed materials from a secure environment, according to intelligence and security officials close to the investigation.

Carter declined to delve into details, saying the assessment was still ongoing. But he added: "I can just tell you right now the damage was very substantial." [....]