The Iraq war has not been a mistake. There was a miscalculation, it being assumed that the US invasion would be quick, easy and dearly welcomed by appreciative Iraqis. Instead the US has faced a bitter, destructive, protracted and costly conflict. There was a "mistake" in terms of operational expectations but Bush achieved what he intended and Obama is faithfully carrying on with the mission. The Bush-Cheney-Rumsfeld think tank, Project for a New American Century, had called for an invasion of Iraq over a year before 9/11. Iraq had to be taken out either with a quick easy war or a long tough one. In any case, the invasion and destruction of Iraq was not a "mistake."
The US destroyed a country that had the audacity to retain control of its own oil supply, kept its entire economy under state control (rather than private corporate ownership), and did not invite the IMF or the giant transnational corporations in. Iraq charted an independent course under a dictator who originally had served the CIA, and had destroyed the left progressive democracy that existed in Iraq since the 1958 revolution. But Saddam then retained control of the country's resources instead of throwing everything wide open to western investors.
Saddam also got out of line on oil quotas (wanting an equitable share of the international market). And he decided to drop the US dollar as the reserve currency and use the Euro instead. So he and his country have been correctly destroyed in keeping with the interests of the US-led global empire. Everything is now privatized, deregulated, devastated and poor--as with Yugoslavia and soon with Libya. Mission accomplished. Pace Tony. Read my book THE FACE OF IMPERIALISM if you ever find time.