Israel was unable to sink the USS Liberty, but did manage to kill or wound almost the entire crew. Thirty-four Americans were killed and 174 were wounded.
There are two explanations for the attack. As Washington has blocked every attempt at an investigation, we do not know which one is correct. Perhaps both are the reasons for the attack.
One is that Israel, which was committing a war crime by mass execution of Egyptian prisoners of war, was fearful that the USS Liberty's surveillance had discovered the crime. The other is that Israel fearing an unfavorable outcome of the war that Israel had initiated intended to blame the attack on the USS Liberty on Egypt, thus bringing the US into the war on Israel's side.
I have written about this attack a number of times, having interiewed sailors and officers on board during the attack, an officer, Captain Ward Boston, who was ordered to produce a cover-up, and Admiral Tom Moorer, former Chief of Naval Operations and Chairman of the US Joint Chiefs of Staff. Frustrated at Washington's coverup, indeed, Washington's complicity in the crime, upon retirement Admiral Moorer convened the Moorer Commission to set the record straight.
The Moorer Commission concluded:
"That there is compelling evidence that Israel's attack was a deliberate attempt to destroy an American ship and kill her entire crew.
"That fearing conflict with Israel, the White House deliberately prevented the US Navy from coming to the defense of USS Liberty by recalling Sixth Fleet military rescue support while the ship was under attack.