Classified National Security Agency programs prevented dozens of terrorist plots, the man in charge of the agency told a Senate panel Wednesday.

National Security Agency chief Keith Alexander also told the panel it was his “intent” to release more specific information about the number of attacks foiled by secret programs collecting data on telephone and Internet records.

Alexander said there were “dozens of terrorist events that these [programs] have helped prevent,” as he stressed the importance of surveillance techniques authorized by the Patriot Act.