Defense Secretary Lloyd Austin was rushed to the hospital on Sunday for symptoms related to a bladder issue, less than a month after a previous undisclosed stay at Walter Reed National Military Medical Center.
Austin, 70, informed the White House, Congress, and Pentagon officials this time.
While he has not transferred authority to Deputy Defense Secretary Kathleen Hicks, she is prepared to assume responsibilities if needed.
Austin faced controversy during his earlier hospitalization on Jan. 1, failing to disclose his prostate cancer diagnosis promptly.
Pentagon officials are reviewing policies, and investigations are ongoing.