WASHINGTON (AP) The Pentagon’s acting inspector general announced Thursday that he would review Defense Secretary Pete Hegseth’s use of the Signal messaging app to convey plans for a military strike against Houthi militants in Yemen.

The review will also look at other defense officials’ use of the publicly available encrypted app, which is not able to handle classified material and is not part of the Defense Department’s secure communications network.

Hegseth’s use of the app came to light when a journalist, Jeffrey Goldberg of The Atlantic, was added to a Signal text chain by national security adviser Mike Waltz. The chain included Hegseth, Vice President J.D. Vance, Secretary of State Marco Rubio, Director of National Intelligence Tulsi Gabbard and others, brought together to discuss military operations against the Iran-backed Houthis.

“The objective of this evaluation is 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 acting inspector general, Steven Stebbins, said in a notification letter to Hegseth.