Secretary of Defense Lloyd Austin speaks during a meeting at the Pentagon on Nov. 22. (Cliff Owen/AP)

WASHINGTON — Defense Secretary Lloyd Austin was admitted to Walter Reed National Military Medical Center on Monday night following complications from an elective medical procedure, the Pentagon announced Friday.

“He is recovering well and is expecting to resume his full duties today,” Air Force Maj. Gen. Pat Ryder, the Pentagon’s top spokesperson, said in a statement.

The Pentagon statement did not specify what the elective procedure was that led to complications.

Deputy Defense Secretary Kathleen Hicks was “prepared to act for and exercise the powers of the secretary, if required,” according to the statement.

Austin, 70, is not the first senior Pentagon leader to be hospitalized in recent months. Gen. Eric Smith, commandant of the Marine Corps, suffered a heart attack on Oct. 29 and was in a Washington hospital for more than two weeks.

In a letter Friday night, the Pentagon Press Association protested the Pentagon decision to wait so long to announce Austin’s hospitalization.

“The fact that he has been at Walter Reed National Military Medical Center for four days and the Pentagon is only now alerting the public late on a Friday evening is an outrage,” the letter said. “The public has a right to know when U.S. Cabinet members are hospitalized, under anesthesia or when duties are delegated as the result of any medical procedure.”

Late last year, Marine Corps Commandant Eric Smith was hospitalized, but the corps did not acknowledge that he had suffered a cardiac arrest until after his release.

Bloomberg News Service contributed to this report