Amid a global furor over US data collection policies, the Obama administration released two documents today describing the scope and what it claims is the legal justification for its monitoring of telephone metadata and internet browsing. The documents portray the National Security Agency's surveillance activities as more limited than recent published reports have made them out to be. But they avoid several key questions surrounding the spying, including which internet companies are cooperating with them and how, why the government has demanded absolute secrecy from the companies they work with, and how the agency's oversight functions work.

According to an NSA memorandum, the agency "touches" 1.6 percent of the estimated 1,826 petabytes of information that flow through servers every day. Of that 1.6 percent of monitored traffic, the NSA said it selects 0.025 percent for review. The agency sought to downplay the amount of data if collects. "If a standard basketball court represented the global communications environment, NSA's total collection would be represented by an area smaller than a dime on that basketball court," the memo says. It represents the NSA's latest damage-control effort in the wake of revelations from documents leaked by former contractor Edward Snowden. Published accounts of the NSA's surveillance programs that draw from Snowden's revelations have depicted a much more comprehensive system for monitoring internet traffic and telephone calls.

Citing a foiled 2009 plot as an example of the system's power

The memo describes the origins of the program, which was created in the wake of a report from the 9/11 Commission that identified gaps in intelligence agencies' ability to collect and share information that might have prevented the attacks. It cites a foiled 2009 plot to bomb the New York subway as an example of the system's power to prevent terrorist attacks, although previous reports have questioned whether NSA surveillance was instrumental to the success. Najibullah Zazi pled guilty to plotting the attack in 2010.

separate white paper from the administration describes its legal rationale for collecting telephone metadata including phone numbers and the length and timing of the calls. It outlines the justification for the program under court precedents and section 702 of the Patriot Act, and describes the reasons that the NSA collects so many call records. In short, the administration says it cannot analyze patterns between calls unless it has a sufficiently large data set. The agency keeps its own copy of the records because in many cases telecommunications agencies purge the records. (The NSA keeps the metadata for up to five years, but telecom companies don't always maintain records for that long.)

"America is not interested in spying on ordinary people."

The documents' release followed a press conference at the White House on Friday afternoon in which President Obama announced plans to increase transparency and public awareness of surveillance programs carried out by US intelligence agencies. The president described four measures; making changes to the Patriot Act, reforming the Foreign Intelligence Surveillance Court, appointing a privacy and civil liberties officer to the NSA, and appointing an independent advisory group to recommend additional changes. "To others around the world, I want to make clear, once again, that America is not interested in spying on ordinary people," Obama said today. "Our intelligence is focused above all on finding the information that's necessary to protect our people, and in many cases, protect our allies." The president also said he would launch a website to describe intelligence agencies' activities in more detail — but if today's document release is any indication, it won't tell us much.

Additional reporting contributed by Sean Hollister.

Thanks, S. Sun!