By Tim Fernholz

The debate is over, the speech delivered, and 30,000 more American soldiers are headed to Afghanistan at the behest of President Barack Obama. He didn't look too happy about it.

No one should be surprised, especially not his supporters. This was the candidate who called Afghanistan the good war, promising to nearly double the number of troops there. Now, after last summer's fraud-riddled presidential election and the contemporaneous increase in the Taliban insurgency's strength, he is trebling America's military commitment to the conflict, going from 32,000 soldiers when he entered office to nearly 100,000 in 2010.

Afghanistan is not an easy case. More than one official has complained it is a task of choosing the least-bad option; many pundits and experts were open about their own difficulties in supporting one plan over another. Beyond policy disagreements, the politics, both domestic and international, left the president painted into a corner. But his speech Tuesday night didn't add much energy to his case for escalation because he did not leave the narrow confines of conventional wisdom on Afghanistan -- conventional wisdom that many, even in Washington, have questioned.

The president based his case, like his predecessor, on the 9-11 attacks launched by al-Qaeda, a group harbored by the Taliban and the original justification for the U.S invasion of Afghanistan. That effort received international backing and the support of an unusually united U.S. public. It was undone by the Bush administration's failure to pursue Osama bin Laden at Tora Bora and the decision to shift of resources to the reckless invasion of Iraq.

In the six years since the start of the Iraq War, the Taliban has regained momentum, challenging the legitimacy of Hamid Karzai's government and fomenting violence in Afghanistan and in Pakistan's border tribal areas. But despite those changes on the ground, it's not clear that the United States' new understanding of counterinsurgency, terrorism, and its own capacity to intervene successfully in other states' conflicts has been applied to the war in Afghanistan. After eight years, the United States' goal in the conflict remains unchanged.

Despite the fact that less than 100 members of al-Qaeda are in Afghanistan, Obama says the U.S. strategic aim remains to disrupt, dismantle, and defeat al-Qaeda in Afghanistan and Pakistan. It is the same goal that he announced in March, and nearly the same strategy, albeit with more resources and some refinements.

But though his speech Tuesday addressed some expected critiques of his policy, he never responded to the most basic questions many have been asking for months: Why is defeating the Taliban central to defeating al-Qaeda or preventing another major terrorist attack on the U.S., especially when the majority of operational planning for the 9-11 attacks happened outside of Afghanistan? Will more troops in Afghanistan push insurgents into nuclear Pakistan, further destabilizing it? And perhaps more important, are American troops and their efforts to impose centralized governance fueling the insurgency rather than dampening it?

To that incomplete list, add concerns about the viability of Afghan President Hamid Karzai as a useful partner. Though his government may be "consistent with Afghanistan's laws and constitution," and his new promises to fight corruption substantial, whether the Afghan people share Obama's trust in their president remains to be seen. Just as worrisome, Obama talked of the civilian surge, but not in great detail. Even as White House officials question the ability of a military solution to succeed without an enormous increase in civilian resources and personnel, it's not clear the government can provide what is necessary.

Assume, though, that Obama's central assumptions are true: A stable, reasonably effective government in Afghanistan is necessary to defeat al-Qaeda and insulate Pakistan from extremists, and U.S. military force is capable of creating it. The White House hopes this "surge," as they themselves now call it, will create an "inflection point" as international forces manage the conflict with the Taliban until Afghan armed forces are trained enough to engage them directly, allowing U.S. troops to begin returning home in the summer of 2011.

There is nothing settled about that time line -- already many on the left are expressing doubts the troops will leave then, and some on the right fret that every soldier will be pulled at that not-too distant date. But that benchmark ought to give some scant hope: While the much-analogized Iraq surge ultimately failed to achieve the needed political reconciliation along with its hard-won security gains, it was the rapid approach of a U.S. benchmark for withdrawal -- and a political climate in the U.S. inclined to let that withdrawal proceed -- that urged Iraqi lawmakers to begin resolving their problems.

The Taliban like to claim that they have nothing but time, that they will wait until the U.S. withdraws to stake their claim on the country, even as many in the national-security community note that pernicious elements in Afghan society have little incentive to bargain with Karzai while it appears he will ultimately lose this civil war. We should hope that Obama is right -- that his surge will give a coercive strategy against the Taliban teeth, and his weak deadline, which may harden along with public opinion against the war, makes Karzai a willing cooperator.

But even that calculation depends on whether the unquestioned central assumptions of this war prove true. Obama's failure to address them in his speech will embolden those in his own party who will continue the debate by proposing a new tax to pay for the war, forcing hard budgetary choices to go along with the difficult decisions of strategy. The speech will not reassure the doubters, nor does it represent a broad change in the direction of U.S. foreign policy in Afghanistan. It does offer, in its recognition of the limits of American power and the reality that we must leave that country someday, more realism than in the previous administration.

The last year has surely disabused Obama of many notions he held before becoming president. Nonetheless, his stubborn insistence on many fronts -- that Congress is an effective producer of public policy, that reasonable outreach to Republicans will pay dividends -- have proved maddening to friends and critics alike. Tonight, he recalled the national consensus after 9-11. "I refuse to accept the notion that we cannot summon that unity again," he said. Already, though, Republicans have begun to attack his plans; we won't see such unity without another crisis. But is Obama's denial of that reality a noble aspiration -- or is it a naiveté? You could ask the same of his entire Afghanistan policy.