Defense Secretary Lloyd Austin was put under general anesthesia on Monday at the hospital for a non-surgical procedure to treat an "emergent bladder issue," his doctors said in a statement.
They said he will be able to resume his normal duties Tuesday and that "a prolonged hospital stay is not anticipated."
Austin's hospitalization, which began Sunday, was the secretary's third since his diagnosis of prostate cancer last December. Pentagon Press Secretary Maj. Gen. Pat Ryder couldn't say Monday during a press briefing what type of medical procedure Austin received, and whether his bladder issue was a complication from his Dec. 22 surgery for prostate cancer or an unrelated matter.
Ryder did say the secretary no longer required further treatment associated with his cancer diagnosis other than physical therapy to address lingering leg pain.
"He is expected to make a full recovery," he said.
The Pentagon had announced last week that Austin would be traveling to Brussels to attend a monthly meeting of the Ukraine Defense Contact Group, the more than 50 countries providing military aid to Ukraine, and a separate meeting of NATO defense ministers.
Ryder said the meeting would now be virtual.
Austin's hospitalization was made public shortly after his security detail took him to Walter Reed National Military Medical Center on Sunday. Ryder said the White House was notified in advance of the secretary being driven to the hospital.
"At approximately 4:55 pm today, Secretary Austin transferred the functions and duties of the office of the Secretary of Defense to Deputy Secretary of Defense Kathleen Hicks," Ryder said in an earlier statement. "The Deputy Secretary of Defense has assumed the functions and duties. The Chairman of the Joint Chiefs of Staff, the White House, and Congress have been notified."
Late Sunday night, Austin's doctors at Walter Reed -- Dr. John Maddox and Dr. Gregory Chesnut -- said he had been admitted to the critical care unit.
"Earlier today, Secretary of Defense Lloyd J. Austin III was transported by his security detail to Walter Reed National Military Medical Center to be seen for symptoms suggesting an emergent bladder issue. Tonight, after a series of tests and evaluations, the Secretary was admitted into the critical care unit at Walter Reed National Military Medical Center for supportive care and close monitoring," their statement read.
The defense secretary previously underwent a minimally invasive surgical procedure for prostate cancer on Dec. 22, which led to a urinary tract infection and serious intestinal complications. He was hospitalized again on Jan. 1, but the White House didn't learn of it for three days -- secrecy that sparked intense scrutiny and criticism.
"I should have told the president about my cancer diagnosis, and should also have told my team and the American public," Austin told reporters earlier this month. "I take full responsibility. I apologize to my teammates and to the American people."
Austin also spoke in personal terms about his health challenges.
"The news shook me, as I know that it shakes so many others, especially in the Black community. It was a gut punch," he said then. "And frankly, my first instinct was to keep it private. I don't think it's news that I'm a pretty private guy. I never like burdening others with my problems. It's just not my way."
President Joe Biden has publicly faulted Austin for not informing him earlier of his hospitalization after his January cancer procedure, but also told reporters that he still had confidence in Austin.
Austin has said he directly apologized to Biden and told him he was "deeply sorry" for not letting him know of his diagnosis immediately.
An internal review as well as an investigation by the Defense Department inspector general are ongoing.
ABC News' Alexandra Hutzler contributed to this report.
Defense Secretary Lloyd Austin cancels overseas trip following hospitalization originally appeared on abcnews.go.com