Backlash on social media criticising the appointment of the first woman to lead the Australian army has been described as 'despicable', as experts say more work is needed to improve representation across defence.

Susan Coyle, current chief of joint capabilities, will be the first woman to be appointed head of any branch of the Australian Defence Force when she steps into the role of chief of army in July.

Defence Industry Minister Pat Conroy hit back at social media commentary that accused the appointment being one of diversity and inclusion.

'It's despicable and disgraceful,' he told ABC Radio on Tuesday.

'She's incredibly professional, intelligent, a soldier who lives the values of the Australian Defence Force.

'She was selected because she was the best candidate.'

Mr Conroy said anyone spreading hate needed to 'have a good, hard look at themselves' and look at her extensive qualifications.

Lieutenant General Coyle enlisted as a soldier in the army reserves in 1987 and has since been deployed to East Timor, the Solomon Islands and Afghanistan.

In 2020, she was the first woman to command the joint task force for all Australian operations in the Middle East.

Announcing the appointment, Defence Minister Richard Marles revealed Lt Gen Coyle told him, 'you cannot be what you cannot see'.

'Susan's achievement will be deeply significant to women who are serving in the Australian Defence Force today and women who are thinking about serving ... in the future,' he told reporters on Monday.

Mr Marles is set to address the National Press Club in Canberra on Thursday, when he will launch the 2026 National Defence Strategy and Integrated Investment Program.

He is expected to announce the federal government will invest up to $15billion in uncrewed and autonomous systems for the defence force, including drones, in the next decade.

While there would be much focus on what the appointment means for women, defence expert Jennifer Parker said Lt Gen Coyle's impressive service during her career must be acknowledged.

'Men and women, particularly those within the ADF, should be very proud of this day... Lt Gen Coyle has significant operational and professional experience and has led a range of commands throughout her career,' Ms Parker told AAP.

'It has taken us too long to get here, and I think we shouldn't take this as read that everything is solved in terms of representation across the ADF.

'We still need to focus on making sure we have opportunities for women and people with different backgrounds.'

Ms Parker, who served in the Royal Australian Navy for more than 20 years and is an expert associate at the ANU National Security College, said it was only in 2013 that restrictions on women serving in all defence roles were removed.

'We should reflect on how much things have changed, but also that there is still more to do,' she said.

'It's incredibly important for women to see the opportunities available to them... this is a significant moment for the army, but I wonder how long it will still take for a woman to be appointed the head of the navy or air force.'

Lt Gen Coyle's appointment comes as the defence force grapples with allegations from female veterans about sexual abuse and harassment experienced during their service.

About 2500 women have joined a landmark class action case against the Commonwealth, alleging a culture of systemic sexual abuse, harassment and discrimination within the ADF.

Changing a culture within any organisation required more than one significant appointment, Ms Parker said.

'This is a complex thing. Culture is ever evolving... (this announcement) is a signal of things going in the right direction, but there are still changes to be made,' she said.

'I'm not sure one moment signifies that a culture has changed. It's about constant small changes.'

1800 RESPECT (1800 737 732)

National Sexual Abuse and Redress Support Service 1800 211 028