The Washington Post has the latest document leak from Edward Snowden, revealing that the NSA has been collecting hundreds of millions of contact lists from email, social media, and IM accounts around the world—including those of Americans. The agency then uses those lists to uncover and map connections and relationships between with its targets. In one day last year, it harvested 444,743 email address books from Yahoo, 105,068 from Hotmail, 82,857 from Facebook, 33,697 from Gmail and 22,881 from other sources, according to an NSA document. Those are described as typical numbers, which puts the annual total of lists collected at more than 250 million.
Although the collections happen overseas, intelligence sources confirm to the Post that the contacts of US citizens are caught up in the sweeps. One official, however, says Americans are protected because "we have checks and balances built into our tools." And though many of the email and IM services plundered are run by US companies—like Google, Facebook, and Microsoft—the NSA is able to bypass them by collecting the data from offshore Internet switches. "We have neither knowledge nor participation in any mass collection of webmail addresses or chat lists by the government," say a Google spokesperson.