US officials are investigating the leak of secret documents related to Israel’s preparations to respond to Iran’s ballistic missile attack on October 1. The documents were published on a pro-Iranian Telegram channel.

Officials have confirmed the authenticity of the documents and apologised to Israel for the leak, according to Israel’s public broadcaster, Kan News. However, Axios reported that the Pentagon and the Office of the Director of National Intelligence declined to comment on the matter.

The documents, dated October 15 and 16 respectively are marked top secret and for viewing by the “Five Eyes” only, namely the United States, Australia, Canada, New Zealand and the United Kingdom, Kan News reported.

Axios reported that the documents include a Visual Intelligence report by the Department of Defense National Geospatial-Intelligence Agency that had been passed around US intelligence agencies earlier last week.

The documents detailed the transfer of munitions to Israeli Air Force bases and other preparations for a likely attack on Iran, including a large training exercise last week and movements by Israeli drone units.

The documents were posted by pro-Iranian Telegram channel “Middle East Spectator”. The channel released a statement saying it had no connection with the original leaker. “Furthermore, we assumed the documents were floating around elsewhere on Telegram, making them part of the public domain,” it said.

Axios noted that the leak may be an attempt to “disrupt” Israel’s attack plans and revealed close spying by U.S. intelligence on Israel, including the use of satellites.

A US official told Axios that while the leak was deeply concerning, it would not influence Israel’s operational plans against Iran.

The Israeli defence establishment takes the leak very seriously, a senior Israeli official told the news site.