NSA Director Keith Alexander said, however, nothing the agency does can be fairly described as “spying on Members of Congress” or U.S. politicians, according to a letter dated Jan. 10.

The director said the agency could not cull its database because it can only access records that are reasonably suspected to be linked to a foreign terrorist group.

“For that reason, NSA cannot lawfully search to determine if any records NSA has received under the program have included metadata of the phone calls of any member of Congress, other American elected officials, or any other American without that predicate,” Alexander said.

Alexander was responding to Sen. Bernie Sanders (I-Vt.) who sent a letter to the director earlier this month asking if the agency had spied on members of Congress. Sanders had classified the collection of metadata under an NSA program — including call times, duration and phone numbers — as spying.