Pentagon chief received treatment for an infection following surgery for prostate cancer.

Austin, 70, was admitted to Walter Reed National Military Medical Center on December 22 for prostate cancer surgery, but due to an infection, he was hospitalised again on January 1 and admitted into intensive care.

Doctors said he remained in the hospital due to ongoing leg pain from the infection so he could get physical therapy.

He was dismissed on Monday and is expected to work from home as he recovers, the Pentagon said in a statement.

Biden and senior administration officials were not told about Austin’s hospitalisation until January 4, and Austin kept the cancer diagnosis a secret until January 9.

Biden said that while Austin’s decision not to share his hospitalisation was a lapse in judgement, it did not change his confidence in him.

However, the lack of transparency about Austin’s hospitalisation triggered administration and Department of Defense reviews on the procedures for notifying the White House if an official needs to transfer decision-making authorities to a deputy.

Austin’s secrecy also drew criticism from members of Congress on both sides of the political aisle.

Representative Mike Rogers, an Alabama Republican and chairperson of the House of Representatives Armed Services Committee, said he had opened a formal inquiry into the matter.

Others have called for Austin to resign, including former President Donald Trump, also a Republican, but the Democrat-run White House has said the secretary’s job is safe.

During Austin’s time at Walter Reed, the US launched a series of military strikes on the Houthis in Yemen due to their attacks on commercial vessels in the Red Sea.

From his hospital bed, Austin juggled calls with senior military leaders, including General Erik Kurilla, head of US Central Command, and White House meetings to review the order and ultimately watch the strikes unfold over secure video.