War hero Ben Roberts-Smith says the top of the Australian Defence Force need to go for shamefully protecting their own careers at the expense of rank and file soldiers.

In forthright comments from Australia's most decorated former soldier, Mr Roberts-Smith said he could no longer recommend young Australians join the Defence Force under its current leadership, who are failing to support veterans.

"My opinion is the Australian Defence Force needs good young Australians … but when you look at what is happening at the moment it gives me pause to think, 'Is it a good option for somebody to do that,' knowing that at any point you could be injured, leave and not be supported in a way that is expected and that you should be supported because you have chosen to serve," he said.

"So from my perspective at the moment, it would take serious consideration before you would be advising people to (join the ADF).

"I say that (but) it could change very quickly because it's all about the leadership."

Asked if there needs to be new leadership at the very top of the Defence Force, the Victoria Cross and Medal of Gallantry recipient gave a one-word answer: "Absolutely."

In a situation Mr Roberts-Smith described as "shameful", he said today's returning soldiers were being treated as poorly as Vietnam veterans were - but today it was owing to the military leadership.

"I actually do think it's shameful, and I say that because this is a lesson that Australia learnt a long time ago, and I think one of the worst examples of this is the Vietnam veteran issue that we faced," he said.

"The Vietnam veterans came back and were treated horrendously by this country … because the politics were not understood.

"In today's military, the civilian community and Australians in general are supportive of their military and were through the whole time we were in Afghanistan and Iraq and that's always been acknowledged. Their support has been great, and what it appears to be now is we're actually being let down by our own military."

Mr Roberts-Smith said a royal commission into veteran suicides would allow an open and transparent look at the leadership of Defence, who he accused of protecting their own careers rather than helping soldiers suffering psychologically.

"The culture has always been this reactive self-protection from the senior leadership," he said.

"I think the posting cycle of our senior leadership being two or three years puts us in a position where our leaders, because of it becoming a bureaucracy, are beholden to that bureaucracy and also answering to government.

"So because of that, instead of worrying about the men and women that serve in the Defence Force, they're worried about protecting their patch and that to me is unacceptable.

"They should be leading the military in a way that the men and women who are serving this country deserve."

Mr Roberts-Smith said the disconnect between Defence and the Department of Veterans Affairs is where the system falls over, with veterans "falling through the cracks" and potentially facing issues such as suicide. "Quite frankly, we can't afford to get it wrong," he said.

"It needs to be done correctly all the time because if it leads to an issue that the veteran faces and if it leads to their suicide then that is an unacceptable outcome."

Mr Roberts-Smith said Defence does not look at veterans as part of their own any more.

"If people are prepared to offer their life up for service then we have a duty of care, as a country, as a nation, to ensure they are looked after for their service," he said.

Mr Roberts-Smith has strongly denied war crimes allegations levelled against him and has launched defamation action against Nine-owned Fairfax newspapers.

Watch Sharri Markson's full interview with Ben Roberts-Smith on Sky News on Friday at 8pm.