A Pentagon watchdog has determined that U.S. Defense Secretary Pete Hegseth risked exposing classified information when he passed details of a planned U.S. strike in Yemen over the messaging app Signal, multiple media outlets reported Wednesday.

The Pentagon inspector general found that the information Hegseth relayed originated from a U.S. Central Command planning document that was marked Secret/NOFORN at the time, meaning it was barred from release to any foreign national, said the reports, quoting sources familiar with the affair.

According to the sources, the watchdog concluded that sharing those operational details on a commercial platform could have endangered U.S. forces preparing for the strike.

An inspector general report stated that Hegseth should not have used Signal and that senior Defense Department officials need better training on protocols, the sources were quoted as saying.

"The Inspector General review is a TOTAL exoneration of Secretary Hegseth and proves what we knew all along -- no classified information was shared. This matter is resolved, and the case is closed," Pentagon spokesman Sean Parnell told the media in response.

Hegseth maintains his original classification authority, which allows him to unilaterally declassify information, said a CNN report.

Hegseth reportedly shared detailed information about forthcoming strikes on March 15, including the flight schedules for the F/A-18 Hornets targeting the Houthis in Yemen, in a private Signal group chat that included his wife, brother and personal lawyer.

On the same day, Hegseth also sent a message in another Signal chat -- one that included The Atlantic's editor-in-chief, Jeffrey Goldberg -- sharing operational details about impending strikes on Yemen, scheduled to occur within two hours, Goldberg revealed in an article on March 24.

Hegseth's wife, Jennifer Rauchet, a former Fox News producer, is not a Defense Department employee, while Hegseth's brother Phil and his personal lawyer, Tim Parlatore, both have jobs in the Pentagon, according to a New York Times report.

Hegseth's use of the Signal messaging app to discuss sensitive military information drew criticism and prompted a probe by the Pentagon watchdog.

An unclassified version of the inspector general report is set to be publicly released Thursday, CNN reported, adding that a classified version was sent to the U.S. Congress on Tuesday night.