The documents are attributed to the U.S. Geospatial Intelligence Agency and National Security Agency, the reports say.
The investigation by U.S. officials will assess who had access to the documents, and whether it was an intentional leak or if they were hacked, according to the reports.
One of the documents says the Israeli air force is continuing to prepare for a strike on Iran, and conducted “a second large-force employment exercise,” according to the reports. The air force is “likely to practice air-to-air refueling and combat search and rescue operations with a large number of aircraft,” the reports cite the document as saying.
The other document details how the Israel Defense Forces is continuing its munitions preparation “certainly for a strike on Iran,” according to the reports.
The documents appeared on the Telegram channel Middle East Spectator, which is described as pro-Iranian, and the linked X account shows it located in Iran.
In a written statement, Middle East Spectator said “the documents first appeared in a private Telegram group,” before it received them in private message.
It was unclear what impact the leak may have on any Israeli military planning for a possible strike on Iran, or on Israeli-American relations.