By Paul Reynolds
World affairs correspondent BBC News website
The war in Iraq was supposed to be over long before now.
Bush saw the war of the "advance of freedom"
It was not supposed to provoke a conflict between Sunni and Shia or stir up an al-Qaeda hornet's nest.
Nor was it supposed to alienate much of the rest of the world from US foreign policy, which post 9/11 was on the crest of a wave of sympathy.
It was intended, its proponents argued, to remove a threat to world peace and to plant the flag of freedom in a Middle East democratic desert.
The critics countered that the threat was an illusion, that the US was invading illegally and sought control over the region and Iraq's oil.
The Iraq invasion was also part of President Bush's doctrine of pre-emption and of his hopes for what he called the "advance of freedom".
In a speech in November 2003 he declared: "Iraqi democracy will succeed - and that success will send forth the news, from Damascus to Teheran - that freedom can be the future of every nation."
The war was not supposed to provoke several years of bloodshed
His doctrine, under which a pre-emptive attack is justified even if the threat is not critical, has been another casualty of the war.
Dr Dana Allin, Senior Fellow for Transatlantic Affairs at the International Institute for Strategic Studies in London, said: "All three candidates in the US presidential election will move away from it in significant ways.
"To a significant extent the experience in Iraq has discredited the doctrine of pre-emption, though it has not killed it off. But the US will not naively invade again and simply hope everything will turn out OK, as seems to have happened in Iraq."
Hopes rise again
The last chapter on Iraq of course has not been written. After the recent improvements, there are claims that it will still all work out, not unlike the Korean War, which went through its own disastrous phase.
The former White House economist Lawrence Lindsey, who believes the financial cost of the Iraq war is "relatively minor in budgetary terms", still hopes for the best.
He wrote in Fortune magazine: "A stable Iraqi government selected by its own people would be a first in the Arab world. It would suggest that there is a third alternative to the current choice between repressive regimes and Islamic fundamentalism."
One of those who called in 2006, not for a withdrawal but the surge, was Washington writer Frederick Kagan. In the neo-conservative bible, the Weekly Standard, he says it has worked and credits the American commander General David Petraeus and his subordinate General Raymond Odierno:
"When General Odierno relinquished command of MNC-I [Multi-National Corps Iraq] on February 14, 2008, the civil war was over. Civilian casualties were down 60%, as were weekly attacks. AQI [al Qaeda Iraq] had been driven from its safe havens in and around Baghdad and throughout Anbar and Diyala. The situation in Iraq had been utterly transformed."
However, even if the war turns out to be "winnable", its critics dismiss any suggestion that it was "worth it".
David Rothkopf, a former Clinton administration official and now with the Carnegie Endowment in Washington, said: "Declaring this to be a success based on recent improvements is like saying that a person badly disabled by gunshots has seen his wounds heal. The damage has been done.
The Bush administration has faced a public opinion backlash
"Bush's foreign policy has been a failure and it will be judged on Iraq. He will bear responsibility for an unnecessary and costly war that violated international law, alienated allies and distracted us from the core issues of terrorism, Afghanistan and stopping the spread of nuclear weapons.
"This has to be the worst managed foreign policy of any president since the Second World War. Even if in the medium term Iraq becomes comparatively peaceful, would it be worth the cost? I do not think so."
The diplomatic fallout
As for America's standing around the world, the war alienated some major American allies, France and Germany most notably. Others did send troops after the invasion - Spain and Italy among them - but then left as public opinions at home turned hostile.
On the other hand, a number of smaller countries, many of them from the former Soviet block, saw an opportunity to show their loyalty to the US and sent contingents - the Czech Republic, Poland, Georgia and others. For them, a strong and active United States bodes well for their future security.
The war's critics dismiss suggestions that it was "worth it"
In turn, Britain's support for the United States has led to further divisions within Europe. These had an impact in the Lisbon treaty talks about a future foreign policy for the EU, strengthening the British determination to keep it firmly in the hands of individual governments.
The invasion of Iraq also caused alarm bells to ring in Russia. There, a new mood of hostility to the West has developed and the Russians have become wary of American power.
Nor has Iraq sparked the democratic revolution in the Middle East that Mr Bush hoped for. And the Israeli/Palestinian conflict remains unresolved.
Ironically it is Iran, with which the US shares a mutual hostility, that has emerged with greater strength, to the concern of the Gulf Arab states.
The fallout continues.