The United States military warned Australia's defence chief that allegations of war crimes from Afghanistan may affect future cooperation with the SAS and Special Operations Command.
Defence chief Angus Campbell has revealed he was advised in writing about American legislation known as "Leahy Law", which prohibits American forces from providing assistance to foreign units accused of gross violations of human rights.
In March 2021, just months after the release of the damning Brereton inquiry, the United States embassy wrote to General Campbell to inform him of the possible legal concerns.
"I received a letter from the defence attache of the United States Armed Forces based in Canberra to me, indicating that the release of the Brereton report and its findings may initiate Leahy Law considerations," General Campbell told the committee.
Under questioning from independent senator Jacqui Lambie, the defence chief confirmed he had not advised Defence Minister Richard Marles of the letter's existence.
"No, he does not know what I'm telling you here, Senator," General Campbell said.
When pressed further by Greens Senator David Shoebridge, General Campbell repeatedly declined to detail what restrictions the US military might have placed on cooperation with Australian special forces or for how long.
"A lot of serious and important matters come across my desk, and I'm only going to say it once more Senator politely — I do not know the dates, I'll have to take it on notice, thank you," he said.
Later the defence chief corrected his evidence to say that former defence ministers were told of the letter and "then routinely advised from March 2021 through to the conclusion of the issue through advice to the Minister in March of 2022".
Senator Shoebridge criticised the chief's response, saying it was "unacceptable" that he did not know what restrictions had been placed on the SAS by Australia's closest ally.
"When our major ally has advised our chief of defence that they won't work with a key unit of the Australian military and you won't tell us for how long that restriction lasted or what the nature of that restriction was, we have significant problem," Senator Shoebridge said.
The Brereton report released in November 2020 recommended 19 soldiers be investigated by police for the "murder" of 39 prisoners and civilians, and the cruel treatment of two others.
