June 8, 1967 was the worst day in the history of the National Security Agency. On that date, Israeli airplanes and torpedo boats mauled and nearly sank an American spy ship in international waters, killing or maiming most of its crew. This tragedy appears as a footnote to Israelis, an unpleasant sideshow of their victorious Six Day War, while official Washington preferred the embarrassing episode be forgotten. But NSA has never let the Liberty and her ill-fated crew disappear from memory altogether.
The USS Liberty was owned and operated by the U.S. Navy, which euphemistically referred to her as one of its Technical Research Ships, but she really worked for NSA. A converted World War Two freighter, the Liberty was barely a warship, possessing minimal armament for self-defense, and her mission was very hush-hush. She sailed the world collecting signals intelligence on behalf of her bosses at Fort Meade, Maryland. Her hull contained a large top-secret room where sailors of the Naval Security Group, NSA’s Navy component, intercepted and translated foreign communications.
In the mid-1960s, the Liberty sailed from crisis to crisis, wherever NSA needed her on station to collect SIGINT, and the beginning of June 1967 found her off the coast of west Africa. However, the rapidly deteriorating situation in the Middle East required her dispatch to the eastern Mediterranean, where war was about to break out again between Israel and her Arab neighbors.
http://observer.com/2017/06/50-years-ago-nsa-israel-attack-uss-liberty/