By Michael Isikoff, Matthew Cole, and Richard Esposito, NBC News, August 20, 2013

More than two months after documents leaked by former contractor Edward Snowden first began appearing in the news media, the National Security Agency still doesn’t know the full extent of what he took, according to intelligence community sources, and is “overwhelmed” trying to assess the damage.

Officials, including NSA Director Keith Alexander, have assured the public that the government knows the scope of the damage, but two separate sources briefed on the matter told NBC News that the NSA has been unable to determine how many documents he took and what they are [....]

NSA had poor data compartmentalization, said the sources, allowing Snowden, who was a system administrator, to roam freely across wide areas. By using a “thin client” computer he remotely accessed the NSA data from his base in Hawaii.

One U.S. intelligence official said government officials “are overwhelmed" trying to account for what Snowden took. Another said that the NSA has a poor audit capability, which is frustrating efforts to complete a damage assessment [.....]