The USS Liberty incident was an attack on a United States Navy technical research ship (a spy ship), USS Liberty, by Israeli Air Force jet fighter aircraft and Israeli Navy motor torpedo boats, on 8 June 1967, during the Six-Day War. The attack killed 34 crew members (naval officers, seamen, two marines, and one civilian NSA employee), wounded 171 crew members, and severely damaged the ship. Both the Israeli and United States governments conducted inquiries and issued reports that concluded the attack was a mistake due to Israeli confusion about the ship's identity.

The combined air and sea attack lasted 23 minutes and was carried out by air strafing and napalm bombing by four Mirage III and Super Mystères fighters, and gunfire and torpedo launches from the motor boats, one of which impacted the ship. Israeli forces terminated their attack after the torpedo impact, believing the ship to be sinking. At the time, the ship was in international waters north of the Sinai Peninsula, about 25.5 nautical miles (47.2 km; 29.3 mi) northwest from the Egyptian city of Arish.

Israel apologized for the attack, saying that USS Liberty had been attacked in error after being mistaken for an Egyptian ship. Others, including survivors of the attack, dispute this account, and state that the attack was deliberate. Thomas Hinman Moorer, the 7th chairman of the Joint Chiefs of Staff, accused President Lyndon B. Johnson of having covered up that the attack was a deliberate act. In 2004, Ward Boston, who served as chief counsel to the Naval Board of Inquiry that investigated the attack, signed an affidavit stating that President Johnson and secretary of defense Robert McNamara had ordered that the assault be ruled an accident and to reach the conclusion "that the attack was a case of 'mistaken identity' despite 'overwhelming evidence to the contrary.'"

In May 1968, the Israeli government paid US$3.32 million (equivalent to US$30.8 million in 2025) to the U.S. government in compensation for the families of the 34 men killed in the attack. In March 1969, Israel paid a further $3.57 million ($31.3 million in 2025) to the men who had been wounded. In December 1980, it agreed to pay $6 million ($23.4 million in 2025) as the final settlement for material damage to the ship plus 13 years of interest.

USS Liberty was originally the 7,725-long-ton (7,849 t) light civilian cargo vessel Simmons Victory, a mass-produced, standard-design Victory ship, the follow-on series to the famous Liberty ships that supplied the Allies with cargo during World War II. It was acquired by the United States Navy and converted to an auxiliary technical research ship (AGTR), a cover name for National Security Agency (NSA) "spy ships" carrying out signals intelligence missions. It carried out five operations in waters off the west coast of Africa leading up to 1967.

During the Six-Day War between Israel and several Arab nations, the United States maintained a neutral country status. Several days before the war began, USS Liberty was ordered to proceed to the eastern Mediterranean area to perform a signals intelligence collection mission in international waters near the north coast of Sinai, Egypt. After the war erupted, due to concerns about its safety as it approached its patrol area, several messages were sent to Liberty to increase its allowable closest point of approach (CPA) to Egypt's and Israel's coasts from 12.5 and 6.5 nautical miles (23.2 and 12.0 km; 14.4 and 7.5 mi), respectively, to 20 and 15 nmi (37.0 and 27.8 km; 23.0 and 17.3 mi), and then later to 100 nmi (185.2 km; 115.1 mi) for both countries, thereby reducing proximity. However, due to ineffective message handling and routing, these messages were not received until after the attack.

According to Israeli sources, at the start of the war on 5 June, General Yitzhak Rabin, Israeli Air Force (IAF) chief of staff informed Commander Ernest Carl Castle, the American naval attaché in Tel Aviv, that Israel would defend its coast with every means at its disposal, including sinking unidentified ships. He asked the U.S. to keep its ships away from Israel's shore or at least inform Israel of their exact positions.

American sources said that no inquiry about ships in the area was made until after the attack on Liberty. In a message sent from U.S. Secretary of State Dean Rusk to U.S. Ambassador Walworth Barbour in Tel Aviv, Israel, Rusk asked for "urgent confirmation" of Israel's statement. Barbour responded: "No request for info on U.S. ships operating off Sinai was made until after Liberty incident." Further, Barbour stated: "Had Israelis made such an inquiry it would have been forwarded immediately to the chief of naval operations and other high naval commands and repeated to dept [Department of State]."