The Pentagon watchdog has released a report that finds US Defense Secretary Pete Hegseth could have put American troops at risk when he used the Signal app to discuss military strikes in Yemen.
The findings in the 84-page report, by the Department of Defense Office of Inspector General, had been leaked and widely reported before their formal release on Thursday, local time.
The inspector general found Mr Hegseth's use of a commercial messaging app and his personal device did not comply with the department's policies.
The report said:
"The Secretary sent information identifying the quantity and strike times of manned US aircraft over hostile territory over an unapproved, unsecure network approximately 2 to 4 hours before the execution of those strikes.
"Although the Secretary wrote in his July 25 statement to the [Inspector General] that 'there were no details that would endanger our troops or the mission', if this information had fallen into the hands of US adversaries, Houthi forces might have been able to counter US forces or reposition personnel and assets to avoid planned US strikes.
"Even though these events did not ultimately occur, the Secretary's actions created a risk to operational security that could have resulted in failed US mission objectives and potential harm to US pilots."
But the report also said that "issues arising from the use of Signal and other commercially available messaging applications are a [Department of Defense]-wide issue".
The report described the information sent via the Signal app as "sensitive" and "nonpublic". However, it found Mr Hegseth had the authority to declassify anything that could have been classified.
"He took 'non-specific general details' that he determined, as an original classification authority, were either not classified or that he could safely declassify and use to create an 'unclassified summary' to provide to the Signal chat participants," the report said.
The report made only one recommendation, for a review of procedures for classifying information. An attached letter from acting inspector general Steven Stebbins said the recommendation had already been addressed.
But a separate inspector general report, released the same day, recommended improvements to training for the department's senior officials on "the proper use of electronic devices".
Mr Hegseth's use of Signal made headlines after a journalist for The Atlantic magazine was mistakenly added to the conversation in March. He subsequently published its contents.
The conversation, which included other senior administration officials including Vice-President JD Vance, included messages about the strikes' timing and targets, and the aircraft and weapons to be used.
After the report's findings were leaked, Pentagon spokesman Sean Parnell issued a statement that described the review as "TOTAL exoneration" for Mr Hegseth, despite its finding that he violated policy.
