FORT MEADE, Md. — The director of the National Security Agency, Gen. Keith Alexander, said in an interview that to prevent terrorist attacks he saw no effective alternative to the NSA's bulk collection of telephone and other electronic metadata from Americans. But he acknowledged that his agency now faced an entirely new reality, and the possibility of congressional restrictions, after revelations about its operations at home and abroad.
While offering a detailed defense of his agency's work, Alexander said the broader lesson of the controversy over disclosures of secret NSA surveillance missions was that he and other top officials have to be more open in explaining the agency's role, especially as it expands its mission into cyberoffense and cyberdefense.
"Given where we are and all the issues that are on the table, I do feel it's important to have a public, transparent discussion on cyber so that the American people know what's going on," Alexander said.
Alexander, a career Army intelligence officer who also serves as head of the military's Cyber Command, has become the public face of the secret — and, to many, unwarranted — government collection of records about personal communications in the name of national security. He has given a number of speeches in recent weeks to counter a highly negative portrayal of the NSA's work.
Speaking at the agency's heavily guarded headquarters, Alexander acknowledged that his agency, steeped in decades of secrecy, had stumbled in responding to the revelations by Edward Snowden, the contractor who stole thousands of documents about the NSA's most secret programs. But Alexander insisted that the chief problem was a public misunderstanding about what information the agency does and doesn't collect, not the programs themselves.
"We, and that includes the press, have not informed the American people in such a way that they can make a right decision here," he said. "The way we've explained it to the American people has gotten them so riled up that nobody told them the facts of the program and the controls that go around it."
He was firm in saying the disclosures had allowed adversaries, whether foreign governments or terrorist organizations, to learn how to avoid detection by American intelligence and had caused "significant and irreversible damage" to national security.
Alexander, who became the NSA director in 2005, will retire early next year.
Although he acknowledged that the NSA must change its dialogue with the public, Alexander was adamant that the agency adhered to the law.
"We followed the law, we follow our policies, we self-report, we identify problems, we fix them," he said. "And I think we do a great job, and we do, I think, more to protect people's civil liberties and privacy than they'll ever know."