WASHINGTON – President Joe Biden is “deeply concerned” about the unauthorized release of classified documents on Israel’s preparation for a potential retaliatory attack on Iran, a White House spokesman said Monday.

The Biden administration is still not certain if the classified information was leaked or hacked, White House national security spokesman John Kirby said. Officials don’t have any indication at this point of “additional documents like this finding their way into the public domain,” he said. He added that the Pentagon is investigating. U.S. officials had confirmed an investigation by the administration.

The documents are attributed to the National Geospatial-Intelligence Agency and National Security Agency, and note that Israel was still moving military assets in place to conduct a military strike in response to Iran’s blistering ballistic missile attack on Oct. 1. They were sharable within the “Five Eyes,” an intelligence alliance comprised of the U.S., Great Britain, Canada, New Zealand and Australia.

– The Associated Press