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 inadvertently added to a Signal text chain by national security adviser Mike Waltz. The chain included Hegseth, Vice President JD Vance, Secretary of State Marco Rubio, Director of National Intelligence Tulsi Gabbard and others, brought together to discuss March 15 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.

In the chain, Hegseth provided the exact timings of warplane launches and when bombs would drop — before the men and women carrying out those attacks on behalf of the United States were airborne.

The review was launched at the request of Sen. Roger Wicker, R-Miss., chairman of the Senate Armed Services Committee, and Rhode Island Sen. Jack Reed, the committee’s top Democrat.

In congressional hearings, Democratic lawmakers have expressed concern about the use of Signal and pressed military officers on whether they would find it appropriate to use the commercial app to discuss military operations.

Both current and former military officials have said the level of detail Hegseth shared on Signal most likely would have been classified. The Trump administration has insisted no classified information was shared.