Reporter Glenn Greenwald, who broke the story about the National Security Agency’s surveillance program, on Sunday defended prior claims from leaker Edward Snowden that low-level analysts and contractors had access to private communications.

“The NSA has trillions of telephone calls and emails in their databases that they’ve collected over the last several years,” Greenwald said in an interview on ABC’s “This Week.”

“These programs are, are very simple screens, like the ones that supermarket clerks or shipping and receiving clerks use, where all an analyst has to do is enter an email address or an IP address, and it does two things,” Greenwald explained. “It searches that database and lets them listen to the calls or read the emails of everything that the NSA has stored, or look at the browsing histories or Google search terms that you’ve entered, and it also alerts them to any further activity that people connected to that email address or that IP address do in the future.