Several top administrators of the National Security Agency and the F.B.I. have been explaining to lawmakers on Capitol Hill why they feel justified in doing surveillance of people in the United States and abroad.

The testimony in Washington stems from news of the biggest intelligence leak in the NSA’s history. Former two-time Florida Governor and long-time U.S. Sen. Bob Graham has been following the news about the NSA surveillance revelations and the whistleblower behind them, Edward Snowden.

Graham talked about what he calls a fine line between national security and citizen privacy.