The United States is investigating the leak of highly classified intelligence that outlines Israel’s plans for a potential military strike against Iran, according to three sources familiar with the matter. One of the sources confirmed the authenticity of the leaked documents.

The documents, dated October 15 and 16, began circulating on social media after being posted by the Telegram account “Middle East Spectator.” The materials, marked as top secret, were intended only for the US and its “Five Eyes” allies—Australia, Canada, New Zealand, and the UK.

The documents reveal Israel’s apparent preparations for a retaliatory strike on Iran, involving the movement of munitions and air force exercises with air-to-surface missiles. The information was compiled by the National Geospatial-Intelligence Agency and the National Security Agency.

This leak, described as “deeply concerning” by a US official, has triggered an FBI-led investigation alongside the Pentagon and intelligence agencies. It also comes at a sensitive time in US-Israeli relations, especially with Israel’s ongoing military planning in response to Iran’s October 1 missile attack.

One document suggests Israel’s nuclear capabilities, something the nation has never publicly confirmed. It also notes that the US has no indication that Israel plans to use nuclear weapons against Iran.

Mick Mulroy, former deputy assistant secretary of defense for the Middle East, emphasized that if Israeli tactical plans were leaked, it could severely damage US-Israeli trust and future coordination efforts.

While US officials have downplayed the severity of the two leaked documents, the possibility of additional leaks raises further concerns. It is unclear how the documents were made public, whether through a hack or deliberate leak.

This breach follows other high-profile intelligence leaks, including one last year that strained US relations with allies such as South Korea and Ukraine.