Editor's note: Bing West is the author, most recently, of "The Wrong War: Grit, Strategy and the Way Out of Afghanistan." He served as an assistant secretary of defense in the Reagan administration and was a Marine infantry officer in Vietnam.
(CNN) -- President Obama's expected decision to reduce our troop level in Afghanistan from 100,000 to 90,000 by the end of 2011, and to 70,000 by the end of 2012, seems reasonable.
The more important issue -- how to do it -- is likely to be quietly decided this fall based on recommendations from a new military team consisting of the secretary of defense, the chairman of the Joint Chiefs of Staff, the United States Central Command, and the commander in Afghanistan.
Here are the factors that will matter.
First, the United States' goal is to prevent Afghanistan from becoming a terrorist sanctuary as the U.S. draws down. Unlike the situation in the 1990s, Pakistan won't give the Taliban the arms and vehicles for a conventional assault along major highways to seize Kabul. The Pakistanis are in no mood to antagonize the U.S., and our air power would devastate any such overt attack.
Instead, the concern inside our military command is that the Taliban can build momentum in the rural areas. In this scenario, as the Taliban gain control in the countryside, the Afghan army would fall back to the cities and to their home tribes. In essence, the concern is about a collapse of the Afghan army. The Afghan army, not the population's attitude, is the key to stability.
The "surge" strategy decided by Obama in 2009 increased U.S. troops from 70,000 to 100,000. The surge is working in the south, due to U.S. efforts. Aggressive U.S. Marines cleared Helmand Province -- but at a cost of twice as many casualties as elsewhere. If all U.S. forces fight as aggressively as the Marines for four more years, then by the end of 2014 U.S. troops may hold most of the key populated terrain in Afghanistan.
But given that Pakistan remains as a 1,500-mile sanctuary, U.S. troops can't win the war. The Taliban will still be able to attack in 2015, the date when Obama has promised that the U.S. will no longer be in a combat role. This means the real fight starts when U.S. troops leave.
If U.S. troops fight aggressively for four more years, the cost to the U.S. through 2014 may be as high as 1,700 more fatalities and $400 billion. The U.S. is fighting a war of attrition that may force a weakened Taliban to negotiate.
But this fight hasn't won over the people, which is supposed to happen in order to win with a counterinsurgency. In Iraq, that did happen. Sunni Muslims turned against the insurgents and the government was able to take over the fight from the Americans. In Afghanistan, the tribes have not supported the American surge. The tribes along the border survive by being chameleons. They expect the Taliban to return when the Americans pull out.
The attitude of the tribes in Afghanistan has not changed, despite the $18 billion the Senate Foreign Relations Committee reported that we poured into economic projects. Instead, over 10 years we have succeeded in creating a culture of entitlement.
Afghans expect us to fight for them and give them money. The committee report cited 16,000 economic projects initiated by the U.S. military alone, as if its mission were to act as a giant Peace Corps. Most of this money has resulted in no change in the war, and has weakened the willingness of the Afghans to rely upon themselves rather than foreigners.
U.S. military leaders believe our soldiers must fight for several more years, because currently 20,000 Taliban can defeat 200,000 Afghan forces. The reason is that the Taliban believe in their cause and replace leaders from the bottom up, despite their losses to attrition. So the U.S. is developing a large Afghan army to substitute numbers for fighting spirit.
But the U.S. has scant influence in selecting Afghan military leaders. This is a huge and perhaps fatal problem. The Afghan army's will to fight and leadership dwarf all other concerns.
So the major issue is not the modest reduction in the number of troops that Obama is about to announce. Instead, the issue is what the new military team will recommend in the fall as the strategy to accelerate Afghanization.
One option will be the creation of a 20,000-member Adviser Corps. This is more important than continuing a surge to control more terrain that must be turned over to Afghan soldiers who are incapable. We need more advisers at the point of combat to call in fire, so that the Afghan soldiers gain a sense that they can win. Presently, we have too many adviser teams that are too small to go on patrols. The advisers can't infuse confidence in the Afghans unless we bolster the size of the adviser teams from about 20 to 60.
The new military team must evaluate whether the better strategy is to stick with U.S. soldiers doing the fighting, or replace many of our combat units with enlarged adviser teams. Currently, there is one American in Afghanistan for every two Afghan soldiers. The new high-level military team must decide whether a better ratio is one American for every 10 Afghan soldiers.
In addition, for the next 10 years, the U.S. should pay members of the Afghan army directly, without going through unreliable civilians in Kabul to do so. If there is a negotiated settlement, the Taliban will emerge as an armed faction of subversion within the state. But without a settlement, the Afghan army faces a long war. Either way, the Afghan army must be confident of direct U.S.support -- at a cost of $10 billion a year, even when our forces are gone.
The opinions expressed in this commentary are solely those of Bing West.