Originally Published: 05 JAN 24 17:25 ET

Updated: 05 JAN 24 18:21 ET

By Oren Liebermann, CNN

(CNN) — Defense Secretary Lloyd Austin was admitted to Walter Reed National Military Medical Center on New Year’s Day for complications from an elective medical procedure, the Pentagon said Friday.

The Pentagon announced the hospitalization four days after Austin was initially admitted. Maj. Gen. Pat Ryder, the Pentagon press secretary, made no mention of the hospitalization at a news briefing Thursday.

The short statement did not detail what the procedure was or what complications followed the procedure, but it said Austin is “recovering well.” Ryder told CNN that Austin remained in the hospital as of Friday afternoon, but he is expected to resume his full duties later Friday. It’s unclear when he’ll be released from hospital.

Asked why the Pentagon waited four days to notify the public about Austin’s hospitalization, Ryder said, “This has been an evolving situation in which we had to consider a number of other factors” including medical issues and personal privacy issues.

The Pentagon declined to say whether Austin was unconscious at any time during his hospitalization or whether he was ever in critical condition.

As defense secretary, Austin is one of the most critical members of the Biden administration’s Cabinet, and he is the civilian leader of the military, making his one of the most important roles in the national security establishment – particularly as the US military faces increased tensions in the Middle East.

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

Austin’s hospitalization – and the lack of acknowledgement – comes as the US faces a number of overseas national security issues, including attacks on US troops in the Middle East, US naval vessels intercepting Houthi launches from Yemen, and the wars in Ukraine and Gaza.

During Austin’s hospitalization, the US carried out a strike in Baghdad against the commander of a pro-Iran militia. Ryder said Austin gave authorization for the strike before he was hospitalized.

The failure to publicly announce Austin’s hospitalization breaks with past precedent.

When President Joe Biden was hospitalized for a routine colonoscopy in 2021, the White House announced in advance that he would briefly transfer power to Vice President Kamala Harris.

And when Marine Corps Commandant Gen. Eric Smith was hospitalized in late October, the service notified the public within 24 hours that he had suffered a medical emergency that required immediate attention. The Marine Corps then listed the senior officer who would serve as acting commandant in his absence. Within four days, the Marine Corps said Smith was making excellent progress following a sudden cardiac arrest.

Smith is scheduled to have surgery within the coming weeks, which will be followed by a period of rehabilitation. He has said he intends to resume his normal duties.

This story has been updated with additional information.

The-CNN-Wire