(NewsNation) — An aide seeking an ambulance for U.S. Defense Secretary Lloyd Austin asked the dispatcher to have first responders discreetly arrive on the scene before transporting him to a military hospital on the day his controversial hospitalization began.

“Can I ask — can the ambulance not show up with lights and sirens? We’re trying to remain a little subtle,” the aide said, according to an audio recording of a 911 call obtained by NewsNation.

In their response, a dispatcher said that “usually when they turn into a residential neighborhood, they’ll turn them off.”

Names were redacted in the recording of the call, but The Daily Beast, which first obtained the recording, reported the person on the call was an aide to Austin.

Austin, 70, was released from the hospital Monday, following waves of controversy about his trips to the hospital kept secret from the White House.

He was admitted to Walter Reed National Military Medical Center on Jan. 1 after complications from a “minimally invasive” surgical procedure to treat and cure prostate cancer on Dec. 22.

Then, on Jan. 2, he was transferred to the intensive care unit.

The Pentagon came under fire for not disclosing information regarding Austin’s hospitalization and communication lapse that left top Pentagon officials and the White House uninformed for days.

Some Republicans have criticized Austin and demanded his resignation.

President Biden on Friday said that Austin had shown a lapse in judgment for not informing him about the hospitalization, but he still has confidence in his Pentagon chief.

The Defense Department’s inspector general’s office released a memo on Jan. 11 stating it will begin a review this month of the handling of Austin’s recent hospitalization.