The inspector general of the US Department of Defense has launched an investigation into Pete Hegseth’s use of the Signal application to message other top-level officials about military strikes on Houthi rebels in Yemen.

The White House faced a backlash after a journalist was inadvertently added to a group chat – where specific details of strikes were discussed – on the commercial app.

The investigation comes at the request of the Republican-led Senate Armed Services Committee.

The goal of the probe is to determine whether the defence secretary and other staff complied with the department policies on using messaging applications to discuss official business.

The acting inspector general, Steven Stebbins, said in a letter to Hegseth that the watchdog would also “review compliance with classification and records retention requirements”.

The White House faced a host of questions after Atlantic magazine editor-in-chief Jeffrey Goldberg was added to a Signal chat in early March, in which Hegseth discussed the exact timings of planned strikes, along with weapons packages and other details.

Democrats have called for officials – including Hegseth and National Security Adviser Mike Waltz, who created the group chat – to resign over the incident.

The Trump administration maintains the information shared in the chat was not classified.

The inspector general’s letter asks Hegseth to name two points of contact for the investigation within five days, including one government employee who is familiar with the incident as well as a “member of the Senior Executive Service or a General/Flag Officer”.

The review will take place both in Washington DC, and at US Central Command headquarters in Tampa, Florida, according to the letter.

Speaking at a news conference on Friday, Attorney General Pam Bondi said she was aware of the inspector general’s probe.

“Those cases would have to be referred to me,” she said. “They have not been referred to me.”

On 26 March, Senate Armed Services Committee chair Republican Roger Wicker and ranking member Democrat Jack Reed asked the Pentagon watchdog to probe what messages were communicated in the Signal chat, defence department policy on sharing sensitive information on non-government networks and recommendations on actions the government should take.

The senators said the Signal scandal “raises questions as to the use of unclassified networks to discuss sensitive and classified information”.