Shafaq News / The Pentagon's inspector general has said it will investigate the handling of Defence Secretary Lloyd Austin's secretive hospital visit last week.
Mr Austin, 70, was placed in intensive care on 1 January after suffering complications from a late December surgery to treat prostate cancer.
But senior defence officials and the White House did not even learn he was seriously ill until three days later.
President Joe Biden has stood by his defence chief amid growing criticism.
In a memo circulated on Wednesday, inspector general Robert Storch - whose agency is independent from the defence department - said his office will "examine the roles, processes, procedures, responsibilities, and actions related to the Secretary of Defense's hospitalization".
The review, he said, will "assess whether the DoD's policies and procedures are sufficient to ensure timely and appropriate notifications and the effective transition of authorities as may be warranted due to health-based or other unavailability of senior leadership".
It is the third probe to be launched in the aftermath of Mr Austin's health crisis, following a 30-day assessment ordered by the cabinet secretary's own office and a review conducted by the White House.
In addition to its review, the White House has also sent a directive to all cabinet secretaries making clear that they must inform the White House when they are unable to perform their duties.
National security spokesman John Kirby has said the president's "number one focus" is Mr Austin's recovery and that he has no plans of sacking him, but he conceded that the disclosure of his illness had been "suboptimal".
Pentagon officials have struggled to explain why they failed to notify relevant people in the chain of command sooner about the gravity of Mr Austin's illness. One reason, they claimed, was that his chief of staff was sick with the flu.
Congress and the American public were not informed about the hospital visit until 5 January, four days after Mr Austin had been admitted.
And it was not until Tuesday that the Pentagon revealed his cancer diagnosis, including to the White House. Doctors at Walter Reed National Military Medical Center said Mr Austin was suffering from a urinary tract infection that had led to a fluid build up in his abdomen and a backed up small intestine.
(BBC News)