In its statement, which comes as the NSA gears up for a make-or-break legislative battle over the scope of its surveillance powers, the agency pointed to “privacy protections” which it says it keeps on all Americans’ phone records.

The statement read: “NSA’s authorities to collect signals intelligence data include procedures that protect the privacy of US persons. Such protections are built into and cut across the entire process. Members of Congress have the same privacy protections as all US persons. NSA is fully committed to transparency with Congress. Our interaction with Congress has been extensive both before and since the media disclosures began last June.

“We are reviewing Senator Sanders’s letter now, and we will continue to work to ensure that all members of Congress, including Senator Sanders, have information about NSA’s mission, authorities, and programs to fully inform the discharge of their duties.”