Secret NSA spying network alleged in San Francisco skyscraper, Seattle, other U.S. cities

Google Map images of 611 Folsom Street in San Francisco, the alleged location of NSA spying operations. Google Map images of 611 Folsom Street in San Francisco, the alleged location of NSA spying operations. Photo: Google Maps Photo: Google Maps Image 1 of / 25 Caption Close Secret NSA spying network alleged in San Francisco skyscraper, Seattle, other U.S. cities 1 / 25 Back to Gallery

A new report alleges the existence of eight secret National Security Agency spy "hubs" across the U.S., including one building in San Francisco's South of Market neighborhood and locations in Los Angeles and Seattle.

The NSA allegedly uses the "peering centers" to monitor internet users' emails, social media posts and browsing, according to the Intercept report published Monday.

"It's eye-opening and ominous the extent to which this is happening right here on American soil," Elizabeth Goitein, co-director of the Liberty and National Security Program at the Brennan Center for Justice, told the news site.

RELATED: Frontline's expose reveals secrets from Room 641A

The secret operations are carried out inside imposing concrete buildings with few windows, many of which seem built to withstand nuclear attack.

According to the report, the centers process data from AT&T customers and other telecommunications companies. The New York Times first disclosed the extent of AT&T's close relationship with the NSA in 2015, using classified documents obtained by whistleblower Edward Snowden.

The telecom giant engaged in a range of spying activities for the NSA, the Times alleged, but the agency's reach extends beyond AT&T customers, according to the Intercept.

The NSA "exploits" AT&T's relationships with other phone and internet providers "for surveillance purposes," the report alleges, "commandeering AT&T's massive infrastructure and using it as a platform to covertly tap into communications processed by other companies."

One such surveillance hub blends into a cluster of high-rises on the corner of Folsom and Second streets, just a few blocks from LinkedIn headquarters and the Moscone Center.

The NSA activities at 611 Folsom Street have been known since 2006, when an AT&T technician named Mark Klein declared in court that the NSA was monitoring internet traffic from Room 641A. Klein said he had been directed to carry out a "special job" involving the installation of a "splitter cabinet" that copied internet data and diverted it to Room 641A.

NSA would not provide comment to the Intercept on "alleged classified intelligence activities." An AT&T spokesperson told the news site the company is "required by law to provide information to government and law enforcement entities by complying with court orders, subpoenas, lawful discovery requests, and other legal requirements."

Besides San Francisco, other West Coast hubs exist in Los Angeles and Seattle.

The Madison Complex at 420 South Grand Ave. in Los Angeles likely processes telecommunications dating being routed across national networks. A former AT&T employee confirmed the building's status as a "peering" hub to the Intercept.

The Seattle "peering" facility is located downtown near the waterfront, at 1122 3rd Ave. The building was constructed in 1955 and initially served as a switching point for the northwest, the report claims. It appears to be owned by the Qwest Corporation, though AT&T has a presence inside.

It is "possible" the Seattle outpost processes communications transmitted between the West Coast and Asia, via the undersea cable Pacific Crossing-1.

In addition to the three West Coast hubs, the Intercept alleges secret NSA operations in AT&T facilities in Chicago, New York City, Washington DC, Atlanta and Dallas.

Read the full Intercept report here.

Michelle Robertson is an SFGATE staff writer. Email her at mrobertson@sfchronicle.com or find her on Twitter at @mrobertsonsf.

