Mr Marles was grilled during the defence and veteran suicide royal commission on Thursday about comments he had made relating to the culture within the senior leadership of the Australian Defence Force.

He confirmed issues regarding the timeliness and accuracy of advice, but defended the people working in his department.

"That does not translate to me thinking that people in defence are hopeless, that's a wrong conclusion," Mr Marles said.

"I'm continually impressed by the quality of the people that I'm dealing with both in the department and the defence force generally.

"The quality of the humans involved is high."

Mr Marles said secretary of defence Greg Moriarty and defence force chief General Angus Campbell had been "very important collaborators" in implementing what he described a "standard of excellence".

Asked why he chose to extend their terms if there were cultural problems, Mr Marles pointed to his previous answer where he spoke of their collaboration.

Veterans' Affairs and Defence Personnel Minister Matt Keogh described the performance of his department as "greatly improved".

"This was a department that was frankly under resourced when we came into government; it's now the best resourced it's been in three decades," he said.

Asked about evidence heard earlier in the week that defence didn't have a reliable data set for sexual misconduct, Mr Keogh said it was a "current shortcoming".

He said he had been briefed on the issue and was concerned he may be getting an incomplete picture.

"Those systems need to be better, absolutely," Mr Keogh said.

"It's a frustration that I engage with on a regular basis when trying to understand things that are going on within defence and to understand data."

Mr Keogh said all levels of government would benefit from a body able to bring together and convey the different views held by veterans.

"My department is looking to fund some research around how that could look going forward subject to views that may come out of this royal commission because we think it would be quite beneficial," he said.

Former commander of Australia's special forces Jeff Sengelman earlier said the inquiry had been built on a foundation of sadness.

The retired major general was a driving force in the establishment of the Brereton war crimes inquiry, which found 25 Australians committed up to 39 murders in Afghanistan.

He said the issue of defence and veteran suicide was as "diverse and as complex" as people and there was a time when he thought they were consequences of exposure to war and battle.

"I now realise that it's much, much broader than that," he said.

General Sengelman said the inquiry was built on a foundation of "sadness, sad stories, terrible things" and traumatic events.

"I've got some inside of me," he said.

"Did I make mistakes as a leader, and in hindsight, do I regret them?

"Yes, yes."

General Sengelman spoke about his experience transitioning to civilian life, with a medical appointment leaving him feeling "rubbish".

He suggested considering the merits of restorative justice, as there was a "lot of hurt and pain out there".

"Every story we know affects a lot of people," he said.

The royal commission is holding its final public hearings this month, with a final report to be handed down in early September.

An interim report released by the royal commission in August 2022 made 13 urgent recommendations to the federal government.

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