The United States is investigating the leak of highly classified intelligence regarding Israel's potential plans for retaliation against Iran, according to three sources familiar with the situation. One of the sources confirmed the authenticity of the leaked documents. A U.S. official described the leak as “deeply concerning” in a statement to CNN.

The documents, dated October 15 and 16, surfaced online Friday after being shared on Telegram by an account called “Middle East Spectator.”

Marked as top secret, the documents bear indications that they were intended only for the U.S. and its “Five Eyes” intelligence partners — Australia, Canada, New Zealand, and the United Kingdom. They detail Israel’s apparent preparations for a strike against Iran, with one document, attributed to the National Geospatial-Intelligence Agency, mentioning the movement of munitions by Israel as part of the planning.