Peter Feaver has an important acknowledgment on the subject:
There were good reasons to promote regime change in Iraq and good reasons to oppose it. But the strongest case for the urgency of dealing decisively with Iraq in 2002 hinged on Iraq's WMD arsenal and its pursuit of capabilities to expand that arsenal. Had the true condition of that arsenal (limited) and the true status of the pursuit (ongoing but slower than suspected and put on a somewhat slower track deliberately pending the final collapse of the sanctions regime) been known by the Bush administration, the president's national security team would have pursued other more urgent priorities in the war on terror. And had it been known more widely in Congress, there would not have been such strong bipartisan support for the use of force resolution; all of the major Democratic senators in 2002 with ambitions for the 2004 presidential run supported the use of force resolution because they agreed with the consensus view that Iraq had a formidable WMD arsenal and was seeking to expand it still further. And had it been known more widely in the international community, the argument with our allies would have been over the existence of an Iraqi threat rather than over the best strategy for dealing with it.
I think Feaver's acknowledgment is important because it also casts the post-hoc rationalizing and exculpating that has accompanied Iraq's current stability in the proper light. None of the national security objectives of the invasion were realized, minus the "regime change" so prized by the war's most fervent supporters.
But there's a problem with Feaver's argument as well, and that is the notion that the existence of WMD would have justified a war. Here, obviously, opinions differ widely, but a large part of the WMD argument didn't simply hinge on the mere existence of weapons, but on what Saddam would do with them. We were led to believe, principally by neoconservatives analysts who didn't have much to say about al Qaeda before 9/11, that Saddam would take the unprecedented step of transferring weapons to al Qaeda for use against the U.S.
In other words, we were led into the war on the basis of a hypothetical. World War I and II, Korea, Vietnam, the first Gulf War, Afghanistan - these were military actions taken in response to concrete events. The second Iraq war was not. Many people were not troubled by this use of military power at the time - indeed, they pushed for war precisely because it would be a demonstration of America's willingness to use force outside of traditional norms. And I think this view informs a lot of the cries of "victory" surrounding Iraq - it's not just a rear-guard effort to rehabilitate careers and legacies. It's an effort to resuscitate the idea that military power can and should be used in this fashion.
