The USS Liberty incident was an attack on a United States Navy technical research ship, USS Liberty, by Israeli Air Force jet fighter aircraft and Israeli Navy motor torpedo boats, on 8 June 1967, during the Six-Day War. The combined air and sea attack killed 34 crew members, wounded 171 crew members, and severely damaged the ship. At the time, the ship was in international waters north of the Sinai Peninsula, about 25.5 nautical miles northwest from the Egyptian city of Arish.

Technical research ships were used by the United States Navy during the 1960s to gather intelligence by monitoring, recording and analyzing wireless electronic communications of nations in various parts of the world. At the time these ships were active, the mission of the ships was covert and discussion of the true mission was prohibited. The mission of the ships was publicly given as conducting research into atmospheric and communications phenomena. Their designation was AGTR – Auxiliary, General, Technical Research – but it was more or less an open secret that this was a euphemism and they were commonly referred to as "spy ships".