Since you brought up the subject of SPYING, consider this.
At that time (1967) the US Navy was being severely compromised by the Walker spy ring. All US Naval communications were being read by Moscow as if they were in clear text.
If Israeli intelligence was aware of this then they really had no alternative other than to sink that ship. If the Liberty acquired any information about Israeli movements it would could have resulted in Israel loosing that war. If Liberty had been lost with all hands, then they would simply say that it was a mistake in identity.
The cover-up by LBJ simply means that he was afraid that if the truth of the matter became public, (whatever that truth may have been), it would have been a great embarassment for his administration.
THE SHIP NEVER SUNK. The Israelis attacked it with weapons that were not designed to go against ships and for sinking ships. THEY WERE scrambled to the area. This was no planned operation.
Try again. Walker didn't start working for the Reds until after the Six Day War. And how would the Israelis have known about him?