With al Qaeda dispersed, Afghanistan, though a human tragedy, doesn't matter much to the US or its allies.
Rather than allow the Afghan mission to slide into nation-building, the Obama administration should begin withdrawing US forces from Afghanistan.
Afghanistan originally looked like the good war. Consolidating power in a reasonably democratic government in Kabul was never going to be easy, but the Bush administration tossed away the best chance of doing so by prematurely shifting military units to Iraq. The Obama administration now is attempting the geopolitical equivalent of shutting the barn doors after the horses have fled.
The situation is a mess. The Karzai government is illegitimate, corrupt and incompetent. Taliban forces and attacks are increasing. Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, admits that Afghanistan is "deteriorating".
Yet Barack Obama is sending an additional 30,000 American troops. He argued that "our overarching goal remains the same: to disrupt, dismantle and defeat al Qaeda" and refused to "set goals that go beyond our responsibility, our means or our interests".
Yet the President appears to have done precisely the latter. Even after the build-up, the US and its allies will have only a few thousand more personnel than the Soviet Union did during its failed occupation. And Western forces will be barely one-fifth the numbers contemplated by US anti-insurgency doctrine.
Given its forbidding terrain and independent culture, it is easy to understand why Afghanistan acquired a reputation as the graveyard of empires. Kabul has had periods of peaceful, stable rule, but by indigenous figures who respected local autonomy, as under the 20th-century monarchy.
The only sensible argument for staying is, as Obama put it, "to disrupt, dismantle and defeat al Qaeda". But that already has been done.
Al Qaeda has been reduced largely to symbolic importance, as most terrorist threats now emanate from localised jihadist cells scattered about the globe. US National Security Adviser Jim Jones estimates that there are just 100 al Qaeda operatives now in Afghanistan.
Even if the Taliban returned to power, it might not welcome back the group whose activities triggered American intervention. Nor would al Qaeda necessarily want to come back, since a Taliban government could not shield terrorists from Western retaliation.
Pakistan offers a better refuge, and there are plenty of other failed states — Yemen comes to mind — in which terrorists could locate.
Far more important than Afghanistan is nuclear-armed Pakistan. However, continued fighting in the former is more likely to destabilise the latter than increased Taliban influence.
Some analysts offer humanitarian justifications for intervening. The Afghan people would be better off under some kind of Western-backed government.
However, this is true largely despite rather than because of the Karzai regime. And many of the improvements are merely relative. Moreover, any gains are threatened by the bitter conflict now raging. Estimates of the number of dead Afghan civilians since 2001 exceed 30,000.
In any case, humanitarianism is an inadequate justification for waging war. Washington is full of ivory-tower warriors who have never been anywhere near a military base, yet who busily concoct grand humanitarian crusades for others to fight.
However, the cost in lives and money — as well as the liberty inevitably lost in a more militarised society — can be justified only when the American people have something fundamentally at stake in the conflict. Their interest in determining the form of Afghan government or liberties enjoyed by the Afghan people is not worth war.
Imagine if George W. Bush had announced that his administration was going to sacrifice several thousand American lives, trigger a conflict that would kill tens or hundreds of thousands of Iraqis, spend $US2 trillion or more, strengthen Iran's geopolitical position, damage America's international reputation, and reduce US military readiness in order to organise an Iraqi election.
Likely popular resistance offers one of the strongest arguments for drawing down forces and shifting from counter-insurgency to counter-terrorism. Even if bolstering the Karzai government is feasible, doing so will be a costly and lengthy process, one for which popular support already has largely dissipated in America and among its allies. It makes no sense to embark on a lengthy campaign for which popular patience is likely to be quickly exhausted.
As a state senator, Obama warned against "a US occupation of undetermined length, at undetermined cost, and with unintended consequences" in Iraq. Unfortunately, that looks like his policy for Afghanistan.
War is sometimes an ugly necessity. But most of America's recent wars have turned out to be matters of foolish choice.
Going into Afghanistan was necessary initially, but staying there today is not. The US and its allies should work to bring the conflict to a close.