Who was behind the attack of USS liberty Spy ship in the sixties, Israeli or Egyptian forces? knowing that both denied they did.
There is absolutely no controversy over who attacked USS Liberty: it was the Israeli Air Force and the Israeli Navy. Israel apologised for the attack, and paid compensation.
There is a controversy about the reason for the attack. The official Israeli explanation is that USS Liberty was mistakenly identified as an Egyptian ship. The US Department of Defense investigation
https://en.wikisource.org/wiki/Index:DoD_USS_Liberty_Inquiry_Press_Release_28_Jun_1967.djvu
noted that
The Court produced evidence that the Israeli armed forces had ample opportunity to identify LIBERTY correctly.
The three elements of the controversy are:
Was Liberty misidentified as Egyptian, or did the Israelis attack it knowing it to be a US ship?
If they knew it was a US ship, why did they attack it? Explanations that have been suggested include: to stop radio jamming by Liberty; a general unwillingness to allow an electronic intelligence ship to stay so close to the war zone; and to stop Liberty's eavesdropping from discovered some (unknown) secret of great importance.
Did the US investigation cooperate with Israel in whitewashing the incident?
A good example of the last of these points can be seen in the Moorer Report:
https://en.wikisource.org/wiki/The_Moorer_Report
8. That due to the influence of Israel's powerful supporters in the United States, the White House deliberately covered up the facts of this attack from the American people;
9. That due to continuing pressure by the pro-Israel lobby in the United States, this attack remains the only serious naval incident that has never been thoroughly investigated by Congress; to this day, no surviving crewmember has been permitted to officially and publicly testify about the attack;
10. That there has been an official cover-up without precedent in American naval history; the existence of such a cover-up is now supported by statements of Rear Admiral Merlin Staring, USN (Ret.), former Judge Advocate General of the Navy; and Captain Ward Boston, USN, (Ret.), the chief counsel to the Navy's 1967 Court of Inquiry of Liberty attack;
11. That the truth about Israel's attack and subsequent White House cover-up continues to be officially concealed from the American people to the present day and is a national disgrace;