Defense Secretary Lloyd Austin has been hospitalized since Monday, due to complications following a minor elective medical procedure, Air Force Maj. Gen. Pat Ryder, the Pentagon press secretary, said Friday.

It was the department’s first acknowledgement that Austin had been admitted to Walter Reed National Military Medical Center.

Ryder said Friday that it’s not clear when Austin will be released from the hospital, but said the secretary is “recovering well and is expecting to resume his full duties today.”

He said that this has been an “evolving situation,” and due to privacy and medical issues the department did not make Austin’s absence public.

In a statement, Ryder said that at all times, Deputy Defense Secretary Kathleen Hicks “was prepared to act for and exercise the powers of the Secretary, if required.”

Austin, 70, spent 41 years in the military, retiring as a four-star Army general in 2016.