The Pentagon’s inspector general is opening an investigation into Defense Secretary Hegseth’s use of the Signal app for a group chat during a military operation that accidentally included the top editor of The Atlantic magazine.

The investigation will determine if Mr. Hegseth improperly discussed operational plans and will include a review to see if he was in compliance with classified information and records retention.

The editor, Jeffrey Goldberg, says he was invited to the chat by the national security adviser, Mike Waltz.

The chat surrounded an operation targeting Houthi rebels in Yemen. The magazine published screenshots and transcripts that discussed the operational plans and timing of the strikes.

The Pentagon’s acting inspector general, Steven A. Stebbins, sent a memo to Mr. Hegseth on Thursday to warn him of the inquiry. The letter states the investigation “authorizes us to have access to personnel and materials as we determine necessary to perform our oversight in a timely manner.”

The top Republican and Democrat on the Senate Armed Services Committee demanded the probe last week. Senators Wicker and Reed said in a letter to the inspector general that there should be a full account of what happened, why it happened, and how similar events can be prevented in the future. 

The inspector general is asking Mr. Hegseth to designate two points of contact for the investigation. The initial investigation will be performed out of Washington, D.C. and U.S. Central Command headquarters at Tampa, Florida, but could expand to additional locations.

In the Signal messages, Mr. Hegseth, who maintains that “nobody was texting war plans,” set out, in detail, 31 minutes before the March 15th strike commenced, a blow-by-blow of the coming operation, including the timing of when it would launch and which weapons systems would be deployed.

President Trump has called the incident a simple mistake and that no one would likely be fired as a result. Attorney General Bondi has faced pressure from Democrats to launch an investigation into possible criminal charges, but she has declined to act.