Defense Secretary Lloyd Austin was hospitalized earlier this week for unspecified reasons but is recuperating, the Pentagon said late Friday, after withholding the information for days.

Maj. Gen. Patrick Ryder, the Pentagon press secretary, said that Austin, who is 70, was admitted to Walter Reed National Military Medical Center outside Washington on Monday “for complications following a recent elective medical procedure.”

Ryder did not provide additional details, but said that Austin, a former Army general who was nominated for the high-profile post by President Biden and became the nation’s first African American defense secretary in 2021, was “recovering well and is expecting to resume his full duties today.”

It was not clear when he could be discharged, or why the Pentagon did not disclose Austin’s hospitalization when it occurred earlier in the week.

The announcement came amid heightened tension in the Middle East, where armed groups with links to Iran have launched attacks on U.S. military facilities in Iraq and Syria and on ships operating in the region. A U.S. airstrike in Baghdad on Thursday underscored the risk of deepening instability despite the Biden administration’s attempts to contain fallout from the war between U.S. ally Israel and Hamas militants in the Gaza Strip.

That effort has likewise been challenged by attacks by Iran-linked Houthi militants in Yemen, who have launched missiles at or fired on commercial ships in the Red Sea. On Sunday, a day before Austin was admitted to the hospital, U.S. forces engaged in a firefight with militants when they assaulted a Singapore-flagged, Danish-owned shipping vessel transiting the area. The administration has established a new multinational maritime coalition in a bid to stem the violence.

Austin, who frequently travels internationally, returned from a days-long trip to Israel and elsewhere in the Middle East in late December.

Ryder, in a statement, said that Deputy Defense Secretary Kathleen Hicks had been prepared to exercise the powers of defense secretary if required because of Austin’s medical treatment. In a later email, Ryder said that Austin remained in the hospital and had fully resumed his job responsibilities on Friday evening.

He said that Hicks had “made some routine decisions on Secretary Austin’s behalf” this week.

“Of note, the secretary did not have to affirmatively delegate his duties because by statute, the deputy secretary is automatically authorized to perform the duties of the secretary if he is unable to perform them,” Ryder added.

A senior defense official, speaking on the condition of anonymity to discuss the situation, declined to say what procedure Austin had undergone, or what the subsequent complication had been.

The official said that Austin had been alert Thursday as U.S. forces carried out this week’s Iraq strike, noting that he and Biden had previously authorized the operation.

The Pentagon Press Association, an organization representing media covering the Defense Department, expressed frustration about the department’s “failure to notify the public and the media” about the hospitalization, and requested a meeting with Pentagon leaders to discuss the department’s handling of the matter.

“The fact that he has been at Walter Reed National Military Medical Center for … days and the Pentagon is only now alerting the public late on a Friday evening is an outrage,” the group said in a letter to Ryder and Chris Meagher, another official overseeing Pentagon public affairs.

The press association said that the public has a right to know when Cabinet members are hospitalized, under anesthesia or delegate their duties as the result of a medical procedure. “This has been the practice even up to the president’s level,” the letter said. “As the nation’s top defense leader, Secretary Austin has no claim to privacy in this situation.”

Ryder, citing “an evolving situation,” said that in determining when to issue the announcement, the Pentagon “had to consider a number of factors, including medical and personal privacy issues.”