According to a four-month investigation by The Washington Post, ordinary Internet users significantly outnumber the legally targeted foreigners in electronic communications intercepted by the NSA. Based on the collection of intercepted conversations from U.S. digital networks that Edward Snowden provided, 90 percent of account holders were not the intended surveillance targets. And nearly half of the files included names, email addresses or other details belonging to U.S. citizens.

While analysts at the National Security Agency reportedly masked more than 65,000 references to protect privacy, nearly 900 unmasked email addresses were reportedly linked to U.S. citizens or residents.

“The surveillance files highlight a policy dilemma that has been aired only abstractly in public,” reports The Washington Post. “There are discoveries of considerable intelligence value in the intercepted messages — and collateral harm to privacy on a scale that the Obama administration has not been willing to address.”

The article suggests that the most valuable content points to “fresh revelations about a secret overseas nuclear project, double-dealing by an ostensible ally, a military calamity that befell an unfriendly power, and the identities of aggressive intruders into U.S. computer networks.”

The files also show that tracking alias accounts led to the capture of Umar Patek, a suspect in a 2002 terrorist bombing in Bali, and Pakistan-based bomb builder Muhammad Tahir Shahzad.

However, the intimate details of daily communications of more than 10,000 account holders who were not targeted have also been catalogued.

The material was collected during a period of growth for the NSA’s domestic collection, offering “an unprecedented vantage point on the changes wrought by Section 702 of the FISA amendments, which enabled the NSA to make freer use of methods that for 30 years had required probable cause and a warrant from a judge,” explains the article.

“One program, code-named PRISM, extracts content stored in user accounts at Yahoo, Microsoft, Facebook, Google and five other leading Internet companies. Another, known inside the NSA as Upstream, intercepts data on the move as it crosses the U.S. junctions of global voice and data networks.”

While “incidental collection” of third-party communications is common in surveillance, The Post suggests that the NSA does not always make the same efforts that other agencies do to limit and discard irrelevant data. It also believes that if Snowden’s “sample is representative, the population under scrutiny in the PRISM and Upstream programs is far larger than the government has suggested.”

“Even if one could conceivably justify the initial, inadvertent interception of baby pictures and love letters of innocent bystanders,” said Snowden, “their continued storage in government databases is both troubling and dangerous. Who knows how that information will be used in the future?”