The Biden administration was not told for days that US Defence Secretary Lloyd Austin had been hospitalised, at least one official has told US media.
Mr Austin, 70, was admitted to the Walter Reed Medical Center on Monday due to complications following surgery.
An official told the BBC’s US partner CBS that the White House was not informed of this until at least Thursday morning.
Mr Austin has accepted responsibility for the lack of communication.
“I recognise I could have done a better job ensuring the public was appropriately informed,” he said in a statement.
“I commit to doing better.”
The defence secretary sits just below the president in the chain of command for the US military.
Mr Austin added that it was “important to say: this was my medical procedure, and I take full responsibility for my decisions about disclosure”.
“I am very glad to be on the mend and look forward to returning to the Pentagon soon.”
He is thought to still be in hospital but a defence department spokesperson quoted by the AFP news agency said he resumed his full duties on Friday.
It is not clear how many of his responsibilities Mr Austin has been able to carry out due to his illness, nor the extent to which Deputy Secretary of Defence Kathleen Hicks stepped in to help.
Officials told CNN that she had periodically taken on his duties during his time in hospital, while she herself was in Puerto Rico on holiday.
Hellbound and Down 