A seven-year UK inquiry into the invasion and unsuccessful search for weapons of mass destruction has found the threat posed by dictator Saddam Hussein was overplayed, intelligence was flawed, postwar planning was inadequate and the legal basis for the war was unsatisfactory.
John Howard was Prime Minister when Australia decided to join the conflict, but he insists there was nothing improper about Australia's involvement in the Iraq war.
He says one important conclusion in the UK report is that Britain's Joint Intelligence Committee took ownership of information in the dossier that was presented to the public by then-Prime Minister Tony Blair.
He says there is no evidence that intelligence was improperly included in the UK dossier used to justify the hostilities.
Mr Howard says based on the information available to him, he still believes it was the right decision at the time.
"Clearly everybody regrets the loss of life in any military conflict. I've said before and I repeat it. The hardest decision I ever took as Prime Minister along with my cabinet colleagues was to commit the men and women of the Australian Defence Force to military conflict. It always bothered me, but I believe that the decision to go into Iraq was justified at the time and I don't resile from that because I thought it was the right decision."
The seven-year Chilcot inquiry into Britain's decision to join the war found the threat posed by Iraqi leader Saddam Hussein was overplayed and the intelligence on his country's nuclear capacity, flawed.
It also concluded the legal basis for British involvement in the war was unsatisfactory, but stopped short of declaring it illegal.
Margaret Swieringa headed a parliamentary inquiry into Australia's involvement in the war that reported in 2004.
Ms Swieringa says there is validity in one of the findings in the Chilcot report: that the intelligence on Iraq's nuclear capacity was flawed.
"Certainly I think it was flawed in the sense that it was manipulated to fit a particular political view. That was certainly the case that we found in Australia. I think the lack of proper process is also an issue. We don't know exactly what process took place in Australia because Australia has only had two inquiries, and both of those inquiries looked into the intelligence but nobody in Australia has looked at the decision-making process."
Kellie Merritt is the widow of Flight Lieutenant Paul Pardoel, the first Australian serviceman killed in the military operation in Iraq.
Ms Merritt's husband was on a short-term contract with the British Royal Air Force's Lyneham base when the British Hercules he was flying in crashed in 2005.
"As a family that's lost a loved one, it makes it very difficult when the ceremonies and the shock subside and you're kind of left with contemplating war grief. You start to question ... well, I'm really proud of Paul and his commitment to service, but it doesn't mean that I'm proud of the decision to wage the war."
Ms Merritt is part of a campaign lobbying parliament for an independent inquiry into Australia's participation in the war.
"We saw Tony Blair and John Howard, perhaps not to the same extreme but certainly, um, sensationalising and ramping up the fear that was quite unfounded, and this is where the checks and balances need to be robust."
Former intelligence analyst and now Tasmanian Independent MP Andrew Wilkie says, despite two Australian inquiries into the Iraq war already, he wants a third.
He says both Mr Howard and former foreign minister Alexander Downer should be held to account.
"The fact is that, the invasion of Iraq and the start of a war that continues to this day, not only did it turbocharge al-Qaeda back then but it created the circumstances for the rise of Islamic State. So, the terror threat that we all face in this country right now is a direct result of the decision by the Australian Government under John Howard in 2003 to join in that invasion."
Peter Leahy was the Chief of Army from 2002 until 2008.
He has told the ABC Australia needs to be careful of blindly following its international partners.
"We should be looking at parliamentary discussion, a parliamentary debate and then a resolution out of the parliament about these decisions to go to war. And I would add that, every day we're at war, we are making a decision to stay at war."
(Reporter:) "So you would like to see a new parliament when it begins debate again the various military deployments we have under way right now?"
"I would like to see any parliament debate them."
Retired Major General Jim Molan was Chief of Operations for Coalition Forces in Iraq in 2004 and 2005.
He rejects calls for war-crimes charges to be brought against Tony Blair and John Howard, telling the ABC he doubts they would be successful.
"It is not illegal to be wrong. And that's an important point. People say the war was not legal, but, mainly, they say that because they didn't agree with it. So I suspect now trying to take the ex-prime minister Blair or John Howard to court, I think there may be attempts, and it would go on for another seven years, but really I doubt that it would be successful."
