By Justin Elliott

Headquarters of the NSA at Fort Meade, Maryland.(Photo credit: Wikipedia)

Among the snooping revelations of recent weeks, there have been tantalizing bits of evidence that the NSA is tapping fiber-optic cables that carry nearly all international phone and Internet data.

The idea that the NSA is sweeping up vast data streams via cables and other infrastructure — often described as the “backbone of the Internet” — is not new. In late 2005, the New York Times first described the tapping, which began after the Sept. 11, 2001 attacks. More details emerged in early 2006 when an AT&T whistleblower came forward.

But like other aspects of NSA surveillance, virtually everything about this kind of NSA surveillance is highly secret and we’re left with far from a full picture.

Is the NSA really sucking up everything?

It’s not clear.

The most detailed, though now dated, information on the topic comes from Mark Klein. He’s the former AT&T technician who went public in 2006 describing the installation in 2002-03 of a secret room in an AT&T building in San Francisco. The equipment, detailed in technical documents, allowed the NSA to conduct what Klein described as “vacuum-cleaner surveillance of all the data crossing the internet — whether that be peoples’ e-mail, web surfing or any other data.”

Read More Does the NSA Tap That? What We Still Don’t Know About the Agency’s Internet Surveillance – ProPublica.