The United States has warned that allegations of war crimes against Australian soldiers in Afghanistan could prevent U.S. forces from working with Australia’s Special Air Service Regiment, Australia’s defense force chief said on Wednesday.

Gen. Angus Campbell told a Senate committee that he received a letter from the U.S. defense attache in Canberra in March 2021 suggesting the elite SAS may have been “tainted” by the allegations of war crimes in Afghanistan raised in an Australian war crime investigation report that was made public in 2000, Associated Press reported.

Campbell said “one individual” had his “posted position adjusted” following the letter.

The letter warned that the Brereton report, which detailed “credible information” that Australian soldiers had unlawfully killed 39 Afghan prisoners and civilians, could trigger a U.S. law that prevents the country’s military working with units linked to gross violations of human rights.

“I received a letter from the defense 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,” Campbell said.

Campbell said he did not believe he informed the defense minister at the time and had not informed the current defense minister, Richard Marles.

Campbell was quizzed by senators on why he had not advised successive governments about such a letter from Australia’s most important security treaty partner, AP reported.

Independent Senator Jacqi Lambie asked whether the government should have been advised of such a “pretty big matter.”

Campbell replied: “I think there’s a difference between ‘may’ and ‘does.’ So the defense attache was indicating that it ‘may,’ rather than it ‘does.’”

Campbell later corrected himself, telling the Senate committee that records showed he had informed the previous government’s defense minister in 2021.

The U.S. never applied Leahy Law restrictions to the Australian military and 12 months after the letter marked the “conclusion of the issue,” Campbell said.

Marles’ office confirmed that the current defense minister, whose government came to power in elections in May last year, had not been briefed on the issue.

Marles “is briefed on matters relating to his portfolio as they arise and as is appropriate,” his office said in a statement.

Police in March charged the first Australian veteran for an alleged killing in Afghanistan, three years after the Brereton investigation found that 19 Australian special forces soldiers could face charges for illegal conduct during the conflict.

Former SAS trooper Oliver Schulz, 41, was charged with the war crime of murder in the death of an Afghan who was shot in 2012 in a wheat field in Uruzgan province.

More than 39,000 Australian military personnel served in Afghanistan over 20 years until the 2021 withdrawal.