George F. Will, a man who keeps a bust of the late Sen. Scoop Jackson, the patron saint of foreign-policy hawks, in the foyer of his office, has called for the withdrawal of U.S. ground troops from Afghanistan. Will now publicly joins the 57 percent of Americans who told CNN pollsters that they oppose the war in Afghanistan.

If those of us who still support the war are to overcome public skepticism, we're going to need a better answer than, "Hey—no fair changing your mind!" Unfortunately that's the first answer that Will has received from conservative writers, including my friend and one-time White House colleague Pete Wehner.

The U.S. supposedly won its Afghan war more than seven years ago. Yet today the Taliban is active in more than one-third of the country. The West's goal of extending freedom is undermined by the insecurity, corruption, and misgovernment that plagues most of the population.

President Hamid Karzai's brother is the biggest drug dealer in the country. The runner-up? Probably Muhammad Fahim, the country's former defense minister and still perhaps the most influential figure within the Afghan military establishment.

Effective police are indispensable to successful counterinsurgency. By all accounts, the Afghan police are feared and disliked by the population. Police ignore Taliban activities when they do not collaborate with them. They extort money from the population and collect pay from local drug lords.

The Afghan army is rather better than the police, but for an unreassuring reason: While the insurgency is ethnically Pashtun, the army leadership comes from Afghanistan's other nations, especially the Tajiks. For them, the war continues a conflict that long predates America's arrival in Afghanistan. When I visited an Afghan military training school last year, I asked the recruits about their motives for enlistment. Every one of the dozen men I interviewed had lost a relative in civil wars dating back to Soviet days. Every one of them used the word "Taliban" interchangeably with "Pashtun." U.S. trainers speak optimistically of transforming this ethnic force into a true national army to serve all Afghans. Here's hoping.

Afghanistan is a very difficult place for anyone to govern, outsiders most of all. Its population, estimated at more than 32 million, is larger than Iraq's. Kabul is a city of maybe 3 million, maybe 4 million. Afghanistan is often described as a country bigger than France. In terms of kilometers, that's true. But with its shoddy infrastructure and unforgiving terrain, Afghanistan might as well be its own planet. It can take longer to travel by road to the next town than it takes to travel from Paris to New York. The much-ballyhooed circular highway around the country remains unfinished and unsafe even where it has been completed.

Afghanistan's illiteracy rate exceeds 80 percent; even senior army officers often cannot read. The prevailing political philosophy was bequeathed to Afghanistan by its former Soviet occupiers: "He who does not steal from the state, steals from his family." Even the emancipation of women—the finest American gift to Afghanistan—is visibly corroding, as girls' schools are closed by terrorist attacks.

So: quit now?

No—and here's why not.

American and NATO prestige has been pledged to Afghanistan. A collapse of Afghanistan into warlordism or a narco-state (the likeliest outcome of U.S. withdrawal) would be very costly. And the fact that the West has not done very well in Afghanistan to date does not doom us to failure forever.

As bad as things are, over the past six months we have had our first hopeful news since the heady days of 2002. Not only are more American troops arriving, but U.S. pressure on Pakistan is at last paying off. After years of disengagement or even complicity with the Taliban, Pakistani authorities have belatedly joined the fight to deny them sanctuary.

On Sept. 2, Pakistan reported a major military operation near the Khyber Pass, consisting of an attack on four bases belonging to the Lashkar-I-Islam militant group. These operations are sometimes exaggerated in the retelling, but there's no question that Pakistan has launched an unprecedented level of attacks on Taliban areas this year—one of which succeeded in killing the chief of the Pakistan Taliban on Aug. 23.

Since 2002, the western world has followed a "development first" strategy in Afghanistan, hoping that if the country recovered economically, the remnants of the Taliban would fade away. This year the U.S. is shifting to a new approach, the "security first" strategy that worked in Iraq. And unlike Iraq, there is now hope that the insurgency in Afghanistan will at last be denied a neighboring safe haven in Pakistan.

Our goals in Afghanistan are properly modest. Nobody is looking to elevate Afghanistan into a model anything. Those who serve in Afghanistan all understand the concept of "good enough." Next door, Tajikistan is the second poorest country in Eurasia. Yet its population is literate, and it does not host international terrorist groups. Tajikistan is not much of a democracy and it has suffered from civil war, but it has groped its way to stability and it has not been accused of the kinds of human-rights abuses committed in Uzbekistan. We can look to that kind of future for Afghanistan, if we get the military strategy right.

Is the new strategy right? I won't predict. But it is new, and it deserves a trial before we reach pessimistic conclusions. Wars are ugly and expensive. But losing wars is worse, and worse in ways often impossible to predict in advance. That's a lesson I learned as a young conservative back in the 1970s—in very large part by reading the columns of George F. Will.