Context: On June 8, 1967 during the Six Day War, Israeli aircraft and torpedo boats attacked the USS Liberty, an American intelligence ship operating in international waters off the Sinai, killing 34 crewmen and wounding 171 despite the vessel flying a large U.S. flag and transmitting its identity. Israel later apologized and said the attack was a tragic case of mistaken identity, but many survivors and later analysts have pointed to the length of the assault, the use of napalm and torpedoes, and Israeli surveillance flights earlier in the day as evidence that the ship was well identified, making the official explanation deeply controversial. U.S. investigations ultimately accepted Israel’s account in diplomatic terms, yet dissent within the Navy and among historians has kept the episode alive as one of the most disputed friendly fire incidents of the Cold War.
There's been a lot of theories, but when i went over the Wikipedia sticker a few months ago they included stopping intentional or unintentional relaying of intelligence about Israeli actions, false flag to blame another country and pull the us into the war, and cover up evidence of war crimes.
I'll offer up another completely unsubstantiated theory, simply Israeli intelligence (Mossad) trying to swing dick on Dulles' CIA. Basically "you're not untouchable in our neck of the woods."
Interestingly enough, 14 days before this...: