On Monday, a White House spokesperson said President Biden was "deeply concerned" about the unauthorized release.

The FBI has opened a federal investigation over the leak of top secret U.S. intelligence documents regarding Israel's preparation for an attack against Iran. Why it matters: The leak was one of the most serious security breaches within the U.S. intelligence community in years.

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

The FBI announced Tuesday it was investigating the alleged leak of classified US intelligence documents about Israel's plans for a retaliatory strike on Iran.Iran has been bracing for a response since it unleashed a wave of close to 200 ballistic missiles on Israel on October 1 in retaliation for the killings of Tehran-backed senior figures in Hamas and Hezbollah.

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

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.

The documents, which were marked top secret and detailed Israeli preparations for a retaliatory strike on Iran, have set off a scramble to find out

U.S. troops are arriving in Israel along with a high-tech missile defense system as Israel prepares to strike back against Iran.

The FBI is investigating the public disclosure of a pair of highly classified intelligence documents describing Israel's preparations for a retaliatory strike on Iran, the bureau said on Tuesday.

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.

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