The oversight arm of the Department of Defense will open an investigation into the Signal chat involving airstrikes against Houthi rebels in Yemen, officials said Thursday.

Following a request from the Senate Armed Services Committee, the DoD's inspector general will audit the incident "to determine the extent to which the Secretary of Defense and other DoD personnel complied with DoD policies and procedures for the use of a commercial messaging application for official business. Additionally, we will review compliance with classification and records retention requirements."

The request for an inquiry came last week from Senate Armed Services Committee Chairman Roger Wicker, a Republican from Mississippi, and ranking member Jack Reed, a Democrat from Rhode Island. The committee says it will hold a briefing with the inspector general as soon as its review is complete.

RELATED STORY | Judge orders Trump admin not to delete Signal communications about attack plans

A federal judge has since ordered the Trump administration to preserve all Signal communications related to the strikes.

National Security Adviser Mike Waltz has admitted to mistakenly including the journalist in the chat, taking responsibility for the blunder. However, the subsequent publication of the text messages led to additional scrutiny from lawmakers amid concerns over how sensitive information related to national security is discussed.

According to reporting from Politico, Waltz and his team have used Signal in the past to coordinate at least 20 chats concerning foreign policy in Ukraine, the Middle East, China and other countries. It was not clear whether those chats involved classified information.