“As a result of my review,” she wrote, “I have concluded that the appropriate response is to continue to neither confirm or deny the existence or nonexistence of any intelligence material on your father. To do otherwise when challenged under the FOIA [Freedom of Information Act] would result in the exposure of intelligence information, sources, and methods, which could harm our national security and severely undermine NSA activities in general. For example, if NSA denied having information in cases where we had no such information, but remained silent in cases in which the information existed, it would tend to reveal in which activities NSA was engaged.”