Iraq was America's first pre-emptive war under the Bush national security doctrine. It is also likely to be the last for a very long time - no matter who wins November's US presidential election. The high cost and great controversy have so discredited the assertive policies of President George W. Bush that a diplomatic retreat to the centre seems inevitable. Already gone are the days when Mr Bush could win great applause - as he did only two years ago - by asserting that in foreign policy 'the only path to safety is the path of action. And this nation will act'.
Instead, future American diplomacy will once again rely more heavily on the conventional tools of alliances, the United Nations and other international organisations to find common solutions to common problems. There will be less of what the world has come to see as an impatient, aggressive and unilateral diplomacy, with its underlying threat of force to get quick results.
In fact, this is less a prediction than a recognition of something already well under way. After the US twice failed to create a temporary government in Baghdad, Mr Bush reluctantly turned to a UN diplomat, who got the job done. Backroom bluster about attacking North Korea if it did not give up its nuclear weapons has evolved into laborious six-nation negotiations with the same goal. And no one in Washington seems to be talking any longer of striking Iran or Syria over alleged weapons programmes or aid to terrorists.
On the contrary, Mr Bush has just completed two European trips to plead for more help and understanding in Iraq and Afghanistan. But despite his newly conciliatory manner, the results were meagre - some police training for Baghdad and a few more Nato troops for Kabul. The Bush style and substance have created resentments that the president is finding difficult to overcome.
Some of the White House's troubled policies were unwise at best, such as summarily rejecting the Kyoto environmental treaty without offering alternatives. But others did have a serious rationale. In Washington's view, the September 11 attacks combined radicalism with modern technology, making America vulnerable to suicide bombers armed with chemical, nuclear or other potent weapons. Because cold war strategies of deterrence and containment have little value against shadowy terrorist groups, something new was needed. And that led to the pre-emptive doctrine: find and destroy radicals before they strike first.
The problem is that Saddam Hussein's Iraq did not really qualify. It had no stores of weapons of mass destruction, ties to al-Qaeda terrorists were ephemeral, and it posed no imminent threat to its neighbours, let alone the US. But some Bush advisers were determined to attack anyway, and a small handful led America to war in what has been called a triumph of hope over evidence. However, they had no effective plan for postwar Iraq, leading to today's mess. The real war against terrorism has suffered, and US interests have been hurt.