US Defence Secretary Lloyd Austin will undergo a medical procedure and temporarily transfer power to his deputy, the Pentagon has said.
The procedure is elective, non-surgical, and is not related to his cancer diagnosis.
Mr Austin, 70, was diagnosed with prostate cancer late last year.
He has been criticised for failing to disclose previous hospital stays in December and January.
In a statement on Friday, Pentagon press secretary Maj Gen Pat Ryder said Mr Austin is still dealing with bladder issues that arose from his cancer treatment.
But he said the elective procedure has “no effect on his excellent cancer prognosis”.
Mr Austin will transfer his duties to Deputy Secretary of Defense Kathleen Hicks as of Friday evening while he is treated at Walter Reed National Military Medical Center.
Maj Gen Ryder said the White House and Congress have also been notified.
Mr Austin had previously apologised for failing to disclose earlier hospital stays, which drew criticism from Republicans and Democrats alike over concerns about transparency and security.
Republican Representative Mike Rogers, chairman of the House Armed Services Committee, said at the time that “it’s totally unacceptable that it took three days to inform the president of the United States that the secretary of defense was in the hospital and not in control of the Pentagon”.
The defence secretary is just below the president in the chain of command for the US military and is regarded as one of the most important members of the cabinet.
Three separate investigations were launched as a result of the disclosure failure.
