Department secretary Greg Moriarty addressed the Royal Commission into Defence and Veteran Suicide at a hearing in Sydney on Tuesday.
Counsel assisting Erin Longbottom KC asked Mr Moriarty whether it would be fair to say the department had a "blind spot" on veteran suicide before 2020's Afghanistan Inquiry, also known as the Brereton Report, and other probes.
"No, I wouldn't accept that," Mr Moriarty replied.
"Those reports and our experience of recent years has intensified focus on these issues."
Mr Moriarty acknowledged his own views around veteran suicide were previously "very simplistic and narrow" but have broadened considerably.
He said it remained a "major challenge" and had been given greater emphasis as a wellness issue for the past five or six years.
However, extra resources in mental health and wellbeing have not led to enough improvement, he said.
"I remain very disappointed we have not been able to change some of the underlying statistics," Mr Moriarty said.
"When I look at the challenges that the organisation has in terms of the way in which workplace health and safety incidents are still higher than I would want them to be.
"The reporting of unacceptable behaviours, and I'm referring here to the services, as well as the groups that I have responsibility for."
Karen Bird told the inquiry denying payment for permanent impairment had cost her son Jesse's life. (Darren England/AAP PHOTOS)
Earlier, the mother of Afghanistan veteran Jesse Bird told the commission she believes bureaucratic delays contributed to her son's death.
Mr Bird took his own life in 2017 more than a year after applying for permanent impairment payments, with funds landing in his account weeks after his death.
"Denying the claims actually cost us our son," Karen Bird told the commission.
"Because he died as a direct result of malfeasance and maladministration, his suicide was preventable."
She said gestures such as laying wreaths on Anzac Day and Remembrance Day have not made it any easier for veterans to get help.
"Veterans actually need to be treated like human beings," Dr Bird said.Australian Defence Force chief Angus Campbell will address the inquiry commission later in the week, with the final report due to be handed down in early September.
The hearing continues.
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