Gen. Keith Alexander, director of the National Security Agency, testified before the House Intelligence Committee on Tuesday and vigorously defended collection of telephonic metadata. Alexander assured the committee that, despite widespread public worries about the government collecting private information on innocent Americans, there are ample safeguards in place to protect civil liberties. “These programs are limited, focused and subject to rigorous oversight,” Alexander told Congress. “They have distinct purposes and oversight mechanisms. We have rigorous training programs for our analysts and their supervisors to understand their responsibilities regarding compliance.”

Alexander also reiterated the vital role these metadata-based programs have filled in protecting the U.S. and its allies from terrorist attacks. “In recent years,” Alexander said, “the information gathered from these programs provided the U.S. government with critical leads to help prevent over 50 potential terrorist events in more than 20 countries around the world.” Metadata collection was important to those successes.