President Biden wasn't aware for days that Defense Secretary Lloyd Austin was hospitalized

Defense Secretary Lloyd Austin is taking "full responsibility for (his) decisions" in having the Pentagon announce that he had been hospitalized for days following complications from what was described as a minor medical procedure.

A U.S. official confirmed to ABC News that the White House did not learn about Austin's hospitalization until Thursday night -- three days after he was hospitalized on the night of New Year's Day for complications resulting from what was characterized as "a minor, elective procedure."

The surprise disclosure of Austin's hospitalization had raised questions inside and outside of government about why it was disclosed so late into his medical treatments at Walter Reed National Military Medical Center in Bethesda, Maryland.

During part of his hospitalization, Austin was treated at Walter Reed's intensive care unit, according to the official.

A U.S. Department of Defense spokesperson confirmed Saturday that Austin remains hospitalized but had resumed his duties on Friday night.

In a statement thanking the hospital staff for his medical treatment, he also addressed the concerns about the late disclosure of his hospitalization.

"I also understand the media concerns about transparency and I recognize I could have done a better job ensuring the public was appropriately informed. I commit to doing better," Austin said on Saturday.

"But this is important to say: this was my medical procedure, and I take full responsibility for my decisions about disclosure," he added.

A U.S. official said that Congress was first notified of the 70-year-old's hospitalization on Friday afternoon, shortly before the hospitalization was first made public in a Pentagon press release.

"Secretary Austin is still in the hospital and recovering well," said the DOD spokesperson. "He resumed his full duties last evening. I don't have any updates to provide at this time in terms of when he'll be discharged."

Austin did not have to delegate his authorities since Deputy Defense Secretary Kathleen Hicks -- who has made routine decisions on his behalf -- was automatically tasked with that responsibility, a DOD spokesperson said Friday.

Hicks was in Puerto Rico on a previously scheduled vacation when she assumed those authorities said the spokesperson.

Sen. Roger Wicker, R-Miss., released a statement Saturday evening saying he was glad to hear Austin's condition has improved, however, "the fact remains that the Department of Defense deliberately withheld the Secretary of Defense's medical condition for days."

"That is unacceptable. We are learning more every hour about the Department's shocking defiance of the law. When one of the country's two National Command Authorities is unable to perform their duties, military families, Members of Congress, and the American public deserve to know the full extent of the circumstances," Wicker said.