GEOFF BENNETT: Welcome to the "News Hour."

A Pentagon watchdog report has found that Defense Secretary Pete Hegseth put U.S.

service members at risk when he used the Signal messaging app to discuss a military strike in Yemen earlier this year.

His use of Signal came to light when a journalist was accidentally added to a chat that gave sensitive real-time updates about a strike against Houthi militants.

Nick Schifrin is here to walk us through what we know.

So, Nick, what did the Pentagon watchdog find?

NICK SCHIFRIN: So this is an investigation by the Department of Defense's inspector general mandated by Congress.

It took him months.

And according to a person who has read this document, the inspector general found that the messages that the secretary transmitted were -- quote -- "secret/no foreign."

The definition of that classification level is that unauthorized disclosure could reasonably be expected to cause serious damage to national security and it can't be shared with foreigners.

And the inspector general went on to say, if those messages had been intercepted, it would have endangered U.S.

service members and the mission.

And the reason the inspector general has concluded this is that Hegseth was, as you just said, narrating or really previewing upcoming strikes into Yemen against Houthi rebel leaders on a Signal chat, where "Atlantic" editor in chief and "Washington Week" moderator Jeffrey Goldberg had been accidentally added.

And the detail was extraordinary, times, the types of weapons, exactly who was going to be flying toward Yemen, exactly when.

And they concluded -- quote -- "We are currently clean on OPSEC," short for operational security.

A former senior military official told me this, Geoff, today.

And this was just echoed by the Senate Armed Services Committee top Democrat, Jack Reed, that if a lower-level service member provided that level of information before the launches of manned aircraft with pilots inside those cockpits, that service member would have been court-martialed and discharged.

GEOFF BENNETT: How is the Pentagon responding to all of this?

NICK SCHIFRIN: The Pentagon points to other results inside the inspector general's findings, including these.

The secretary can declassify anything as he sees fit.

And that suggests that Secretary Hegseth's defense is that what he was writing, he was declassifying essentially as he wrote it.

The inspector general also said the secretary provided a small handful of Signal messages to the I.G., but not others.

Hegseth declined an interview with the inspector general and he informed the inspector general that he considers this investigation completely partisan.

And chief Pentagon spokesman Sean Parnell provided this statement -- quote -- "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."

By the way, the inspector general also concluded, Geoff, that Hegseth violated policy by using his personal device for these Signal chats, rather than a government phone.

GEOFF BENNETT: All right, Nick Schifrin, our thanks to you, as always.

NICK SCHIFRIN: Thank you.