Defense Secretary Lloyd Austin is being treated for prostate cancer and suffered complications that led to him being taken to hospital on New Year’s Day where he is still being treated, according to a statement Tuesday from Walter Reed National Military Medical Center. The statement revealed that the cancer was discovered in early December. He underwent a “minimally invasive surgical procedure” on December 22 called a prostatectomy to treat the cancer. “He was under general anesthesia during this procedure. Secretary Austin recovered uneventfully from his surgery and returned home the next morning. His prostate cancer was detected early, and his prognosis is excellent,” the statement read. On January 1, Austin was readmitted to the hospital due to complications “including nausea with severe abdominal, hip and leg pain.” He was found to have a urinary tract infection, the statement said. The Pentagon had been facing intense questions after it was revealed on Friday that he had been admitted to Walter Reed on January 1 and had been hospitalized for days without notifying the public. It was subsequently reported that President Joe Biden, senior national security officials and even Deputy Secretary of Defense Kathleen Hicks – who had assumed Austin’s duties – were not aware of the defense secretary’s hospitalization until three days after he was admitted. But on Tuesday, the Pentagon revealed that Austin had kept the reason for his hospitalization – the cancer diagnosis and the complications arising from his treatment – secret, not just from senior figures at the Pentagon, but Biden himself, raising huge questions about transparency and communications within the administration. National Security Council spokesman John Kirby said Tuesday that Biden only learned Tuesday morning of Austin’s diagnosis – hours before it was disclosed publicly. Previously, Pentagon spokesman Maj. Gen. Pat Ryder told reporters on Monday that the White House was also not notified of Austin’s December 22 procedure. ‘Nobody in the White House knew’ “Nobody in the White House knew that Secretary Austin had prostate cancer until this morning, and the President was informed immediately after,” John Kirby told reporters in a briefing on Tuesday afternoon. Biden was informed by chief of staff Jeff Zients about Austin’s condition Tuesday morning, Kirby said. It’s unclear why Austin did not inform Biden of the diagnosis on Saturday evening when the two talked while Austin was in the hospital. Despite the obfuscation of his diagnosis to the president, Kirby said Biden has “complete confidence” in his defense secretary and plans to keep him in his position through his term, while simultaneously acknowledging the situation was not ideal. “It is not optimal for a situation like this to go as long as it did without the commander in chief knowing about it,” Kirby said. Asked why Austin did not disclose that he was diagnosed with prostate cancer — Ryder said the situation was “deeply personal.” “[I]t’s prostate cancer and the associated procedures are obviously deeply personal,” Ryder said Tuesday during a news briefing at the Pentagon. “And so, again, you know, we’ll continue to work hard to make sure that we’re being as transparent as possible moving forward, and again, wish the secretary speedy recovery.” For the last eight days of Austin’s time at Walter Reed in treating the infection, he “never lost consciousness and never underwent general anesthesia.” Ryder did not answer a question about who decided to not inform Biden that Austin had prostate cancer. “When this happened in December, whose decision was it not to alert the President that the defense secretary had prostate cancer?” a reporter asked during the briefing. “You know, as far as the situation in terms of what the elective surgery was, and the Secretary’s condition, we’re providing that information to you as we’ve received it. We received that this afternoon and we’re providing it to you now,” Ryder said, appearing to say he did not know about the diagnosis until the statement from Walter Reed was released on Tuesday. “So I’ll just leave it there.” Ryder also declined to say if Austin’s chief of staff — who is being identified as the person who failed to notify officials of Austin’s hospitalization last week because she had the flu — knew about Austin’s condition. Ryder did not say if the secretary’s travel would be affected by his procedure or complications, but said Austin is “actively engaged in his duties” and in regular communication with his staff. Austin suffered ‘rare’ complications Whether the procedure was considered elective or more urgent is a matter of how soon it needed to take place, Dr. Benjamin Davies, urologic oncologist and professor of urology at University of Pittsburgh, told CNN. He said it’s also possible there were other options for treatment, such as radiation. It may have been characterized as “essential,” meaning the procedure should take place within three months, he said — but it wasn’t an emergency situation. The complications the secretary experienced, Davies said, are very rare, with a “less than 1% chance this can happen.” According to the American Cancer Society, prostate cancer is the second-leading cause of cancer death in American men, behind lung cancer. While it can be serious, most men diagnosed with prostate cancer do not die from it, and the death rate has declined sharply over the last few decades. Ryder emphasized on Tuesday that there is “nothing more important to us than the trust of the American public that we serve.” “[W]e realize that trust has to be earned,” he said, “and so we’re going to work hard every day to make sure that we are earning that trust, but more importantly, deserving that trust.” This story has been updated with additional developments. CNN’s Kevin Liptak contributed to this report.