So surely it is a good idea to ask what went wrong? The US and Britain - our partners in the invasion - have gone over this question in exhaustive and forensic detail. In Australia, we have simply turned our back and moved on, reluctant perhaps to admit to ourselves that we had any real part in the decisions that led to war. That is simply wrong. We are not responsible for their decisions to invade, but we are surely answerable for our own decision to go along with them. The mistake was ours, too. So what was the mistake? There a several answers because there were several reasons to invade, and they were then, and remain now, deeply muddled. The reason we all debated then, and remember now, was Iraq's weapons of mass destruction (WMD) program. The mistake everyone remembers about Iraq now is that there turned out not to be any WMD in Iraq. I'm sure all three governments involved really believed Iraq had WMD, and so there was a serious intelligence failure there. But that was not the most important mistake. Even if Iraq had the WMD that Bush and John Howard claimed, the invasion would still have been an error. To see why, we have to consider the nature of strategic choices. Politicians sometimes talk as if they can eliminate any risk whatsoever to national security, but that is a fantasy. In the real world, strategic policy is always a matter of balancing costs and risks. If Saddam Hussein had possessed WMD, there would have been a risk of him passing them to terrorists. Howard maintains today that the invasion was justified for this reason. That risk was real enough, but it was always slight, simply because it was hard to see how it would have been in Saddam's interests to give WMD to al-Qaeda. The big strategic mistake about WMD was to believe that removing this modest risk was worth the immense costs of invading, occupying and reconstructing Iraq. That never made sense.

This error entailed a second, more fundamental misjudgment about how much the invasion would cost and where it would lead. Had it been as quick and easy as Donald Rumsfeld expected, then it might have been justified to remove the Iraqi WMD risk. But Rumsfeld's feckless optimism was never justified. Removing Saddam's Baath regime was always likely to be pretty easy. Occupying, governing, stabilising and reconstructing Iraq was always going to be an immense and perhaps impossible task. The nightmare that followed the invasion was not simply a failure of planning or execution by the US and its allies. It was a failure of conception, entirely predictable and entirely predicted. There can be no excuse for Australia's leaders and their civilian and military advisers not recognising this. Had they done so, how could we have gone along with the invasion? But were WMD the real reason to invade? It was clear, even well before the invasion took place, that it was not. For the Washington neo-conservatives such as Paul Wolfowitz who were the invasion's true progenitors, Iraq's WMD were always only a pretext, not a reason. They knew Iraq's supposed WMD did not warrant an invasion. They wanted to make Iraq a pro-US liberal democratic country that would then catalyse the transformation of the entire Middle East so that it would fit their vision of a US-led global order. This plan was not just misjudged. It was barely rational. So here was a third mistake. Did Australian ministers and their advisers understand what was really driving America's decision to invade? If so, did they share its puerile delusions? Or did they think it didn't matter that they were supporting encouraging the US in a grand folly? Which brings us to the final and most fundamental Australian mistake over Iraq. Because, obviously, the main reason we invaded Iraq was to support America. Washington called and Canberra followed. This is not necessarily a mistake in itself. Often it can make good sense to build our alliance credentials by joining military coalitions where the costs and risks are low. The mistake is to follow America without asking searching questions: What are we joining? Why is it happening? Where will it lead? And how might it end? Perhaps more deeply, the mistake is not to ask these questions because our leaders can hardly imagine saying ''no'' to Washington whatever the answers might be.

These questions would have been worth asking again when Washington wanted us to help transform Afghanistan. And they are worth asking again today, as America is again seeking our support for a new military commitment. Barack Obama explained when he visited last month how America is today turning its back on its mistakes in Iraq and Afghanistan and pivoting instead to Asia. Here America is launching a new military initiative to confront and contain China. Our leaders are eagerly agreeing to join in, just as their predecessors did nine years ago over Iraq. Like them, our leaders and their advisers today are only too happy to assume that Washington knows best. Like them, they can hardly imagine saying no. But there is a difference. When our mistakes go bad in Iraq or Afghanistan we can simply give up and come home, as we have done. If we make the same mistakes this time, here in Asia, we will live with the consequences for a very long time. Hugh White is professor of strategic studies at ANU and a visiting fellow at the Lowy Institute. Follow the National Times on Twitter: @NationalTimesAU