Paul Poduska spent four months in Afghanistan in 2009 and another eight months between 2011 and 2012.

During his final deployment, his best friend and fellow sniper Matthew Lambert was killed by an improvised explosive device.

Another three men lost their lives at the hands of a rogue soldier.

Mr Poduska said so many sacrifices were made with soldiers spending months or years away from their families.

"You think about it now and we could have been at home," he said.

"I could have spent birthdays with my kids and spent more time with my partner.

"We're extremely pissed off. Especially because we lost friends of ours on the ground and you think 'well if we didn't go, they'd still be around'."

The Taliban took control of the presidential palace in Kabul on Sunday, almost 20 years after being ousted by a US-led military coalition.

Emboldened by the withdrawal of US troops, they now control all key cities in the country.

Mr Poduska said it was extremely demoralising.

"I'm angry and see it as such a huge waste of time and resources," he said.

"You can see there was no real plan once the US withdrew from Afghanistan. There was no intention to repatriate or keep the local government and systems in place that we'd established over those 20 years. They basically just got up and left."

Mr Poduska said in the weeks before Sunday, he knew it was only a matter of time before the Taliban regained control.

"There was no intention of keeping a large number of troops on the ground," he said.

"As soon as we heard that, everyone across all coalitions that were involved knew they would be rolled. The Taliban knew they were going to leave and within a number of weeks they'd take back everything we tried to do."

Mr Poduska said it was painful knowing 20 years of hard work was gone in just weeks.

"That's probably the worst thing," he said.

"The amount of time we all spent there and what we gained on the ground, it's been abolished within literally two or three weeks. I woke up, went to work, came home and I saw that Kabul had fallen. Done and dusted."

Mr Poduska said he believed the Australian infantry spent too much time mentoring the Afghan National Army (ANA) while on the ground.

"The infantry was too busy babysitting the ANA, making sure they were fighting the right way and not shooting at us," he said.

"We did our research before we went into Afghanistan and we knew that the key mission was probably in question before we even went in there.

"Unless you're going to meet the Taliban with the same force and the same level of severity and violence that they use, you're not going to be able to change or gain anything in that country. It only knows brutality and violence and severe amounts of it."

Mr Poduska said he felt for those still left in Afghanistan.

"Anyone that sympathised or helped any of the coalition forces will now be hunted down," he said.

"Their families and their extended families will literally be hunted down but there's only little bits of pieces coming out about war crimes. We won't hear about that for a long time.

"There's no one on the ground anymore so we don't know what's going on. You fear for them because the Taliban will have lists, they will have their names and they're just going to go around and exterminate them. It's as simple as that."

Mr Poduska said current images of Afghanistan were totally different to the one he knew during his deployment.

"It's totally lawless now. It's gone back to the Taliban rule and they rule with an iron fist," he said.

"Things like schools being set up for females will just be eradicated. They will just annihilate any western influence that's been put into that country. Anything that represented a form of moving forward will be torn apart.

"We were helping them progress but they're just going to totally regress and go back to the barbaric ways of the Taliban."

Mr Poduska said he feared for the mental health of returned Afghanistan soldiers, as well as Vietnam veterans.

He compared the Taliban takeover of Kabul with the fall of Saigon, citing pictures of people scrambling into helicopters or planes at the close of the wars.

"We're seeing the exact same trend as what (Vietnam veterans) went through with their campaign and how that finished. There's so many similarities it's not funny," he said.

"There's so many pictures coming out of Kabul right now of the embassies being evacuated by the US, it's the same pictures, the same people, the same things that are happening."

Mr Poduska, who now works as an apprentice carpenter in Warrnambool, said it was difficult to equate the takeover to life back in Australia.

"As a chippy, it's like you've been building for 20 years, there's all these physical structures you've built over the years and then someone goes along with a bulldozer, scraping all of your hard work off the face of the earth," he said.

"They no longer exist, there's no photos of them, no record and 20 years of your life work is just gone."

Ms Poduska said the takeover was "the icing on the cake" in terms of debilitating mental health among soldiers.

"Our guys are already struggling and then you demoralise them even more," he said.

"This will lower their self-worth, what they have done for their country and all of our hard work on the ground and in training during the lead-up."

RSL Australia president Greg Melick urged veterans and members to "look after their mates" at this time and link in with RSL branches and sub-branches for support.

"The Open Arms counselling and support service is also ready and able to help as needed," he said in a statement.

"It is disappointing to see the hard-earned coalition achievements in Afghanistan now being taken back by the Taliban, and the RSL stands by the dedicated work of all our serving and ex-serving veterans from Middle East operations"

Our journalists work hard to provide local, up-to-date news to the community. This is how you can access our trusted content: