The Israel Air Force warplanes and Israel Navy warships that attacked the USS Liberty on June 8, 1967, at the height of the Six-Day War, were aware that the vessel was an American spy ship, according to new testimony published Thursday in the Chicago Tribune.

The report stated that the U.S. National Security Agency - to which the intelligence gathering ship belonged - was able to intercept IAF communications according to which, at some stage, the pilots identified the ship as American but were nonetheless instructed to push ahead with the attack.

According to the report, some of the transcripts and intelligence information have disappeared, while the rest can be found in U.S. government archives.

Oliver Kirby, the NSA's deputy director for operations at the time of the Liberty attack, is quoted by the Tribune as confirming the existence of the transcripts, saying he personally read them.

"They said, 'We've got him in the zero,'" Kirby was quoted as saying, "whatever that meant - I guess the sights or something. And then one of them said, 'Can you see the flag?' They said 'Yes, it's U.S, it's U.S.' They said it several times, so there wasn't any doubt in anybody's mind that they knew it."

Kirby told the newspaper that the transcripts were "something that's bothered me all my life. I'm willing to swear on a stack of Bibles that we knew they knew."

The report also states that then U.S. defense secretary Robert McNamara ordered jets that had been dispatched to assist the Liberty turned around.

The Tribune quotes J.Q. "Tony" Hart, then a chief petty officer assigned to a U.S. Navy relay station in Morocco that handled communications between Washington and the 6th Fleet, as saying that he listened in as McNamara said, "President [Lyndon] Johnson is not going to go to war or embarrass an American ally over a few sailors."

McNamara, who is now 91, told the Tribune he has "absolutely no recollection of what I did that day," except that "I have a memory that I didn't know at the time what was going on."

Foreign Ministry Spokesman Mark Regev told the Tribune that the attack on the Liberty was "a tragic and terrible accident, a case of mistaken identity, for which Israel has officially apologized."

The USS Liberty was came under attack, first by IAF jets and then some 15 minutes later by Israel Navy warships, while patrolling off the shores of El-Arish in the Sinai Peninsula. 34 American sailors perished in the attack, 26 of them in the naval assault.