President Joe Biden is "deeply concerned" about a leak of classified documents that contain the US's assessment of Israeli plans to attack Iran, White House National Security Council spokesman John Kirby said. Officials have not determined whether the documents were released due to a hack or a leak, Mr Kirby said.

The U.S. is investigating an unauthorized release of classified documents that assess Israel's potential plans to attack Iran.

US investigators are trying to find out how the highly classified intelligence documents were leaked online.

Fox News senior strategic analyst Gen. Jack Keane (Ret.) on the latest from the war in Israel as fighting continues against Hezbollah as the U.S. probes an intel leak of Israel attack preparations.

American officials are trying to determine the source of the leak, which describes military drills and weapons placement, and how damaging it might be.

White House spokesman John Kirby noted that the Pentagon is investigating the incident, but it remains unclear if the classified materials were hacked or leaked.

Israel plans to strike Iran in retaliation for a ballistic missile attack this month. Iranians fear the response will destabilize the economy and stir unrest.

The documents posted on social media have markings that would indicate that they originated from the National Geospatial Intelligence Agency (NGA).

Documents, published online to messaging app Telegram, were marked "top secret," but it is not yet clear if they are authentic.