Australia's defense chief said on Wednesday the United States warned him in 2021 that allegations Australian special forces soldiers killed prisoners and civilians in Afghanistan may trigger a law prohibiting assistance from the United States.
The United States is Australia's biggest security alliance partner and Angus Campbell's comments are the first time it has been publicly disclosed there was a disruption to defense ties.
Asked by Greens Senator David Shoebridge how long the US Department of Defense had suspended engagement with Australia's special forces, Campbell told a parliamentary committee: "There was a precautionary period where we looked to our arrangements."
He did not confirm that engagement had been suspended.
There are currently no restrictions on Australia's special forces working with the US, Campbell added.
Investigations into Australian special forces in Afghanistan
A four-year investigation, known as the Brereton report, found in 2020 that Australian special forces allegedly killed 39 unarmed prisoners and civilians in Afghanistan. Australia referred 19 current and former soldiers for potential criminal prosecution as a result.
Campbell told the committee that he had received a letter in March 2021 from the United States defense attache in Canberra outlining the US concern.
Campbell, responding to questions by the committee, said the letter said "that report, because it had credible information of allegations of what the United States would call gross violations of human rights, may - may - trigger Leahy Law considerations with regards to the relationship between the United States Armed Forces and a partner unit or organization."
Campbell said the United States had wanted to understand "what Australia was doing" in response to the Brereton report. An Australian soldier had his posting adjusted as a result of the "Leahy Law issues," he added.
The US Embassy in Canberra declined to comment.
Leahy Law prohibits the US government from using funds or assisting units of foreign security forces where there is credible information of gross violation of human rights.
According to a US government fact sheet, assistance can be resumed if a government takes effective steps to bring those responsible to justice.
Although current Defence Minister Richard Marles was not aware of the issue, Campbell later said the defense minister at the time was kept informed from March 2021 until "the conclusion of the issue" in March 2022.
A spokeswoman for Marles said he had not been briefed on the matter. "As the Chief of Defence Force confirmed, in March 2021 advice was provided to the CDF and considered by him at the time," she said in a statement.
Australia's military involvement in Afghanistan began in September 2001 and continued until mid-June 2021, the longest engagement by Australia in an armed conflict.