According to NATO, in the fall of 2006 the following was true:
NATO troops dead: 19 out of 20,000
Afghan soldiers and police dead: Over 100
Taliban dead: 1,000 out of 3,000-5,000
Civilians killed by NATO: 53
Civilians killed or kidnapped by Taliban: Several hundred
Civilians fleeing homes due to Taliban in last four months: 80,000
No one's statistics are really trustworthy in war. For example, if we had an accurate census of Taliban troops they'd all be dead now. But, I'm willing to give the numbers the benefit of the doubt for argument's stake, and even to overlook some of the not strictly comparable numbers, such as the lack of numbers regarding civilians killed by Afghan government forces, and the fact that "killed or kidnapped" is not exactly the same as killed.
We also don't know how many Taliban soldiers or how many friendly forces, were captured. From our perspective, a Taliban foot soldier in a prison camp is as good or better than a dead Taliban soldier. The goal is to reduce the numbers of their forces in the field. Are the bulk of the 14,000 people in secret CIA prisons Taliban, or are they civilians from around the world believed to be involved in terrorism, for instance?
What do the numbers show?
1. NATO and the Afghan government are much better at killing their enemies than their enemies are at killing them. The implication is that we kill eight of them, for every one of us that gets killed, and that their forces have taken heavy losses, while ours have taken light losses (one would guess that Afghanistan should have on the order of 75,000 soldiers and police or more, given its population, although we aren't given that number).
2. NATO and the Afghan government are more discriminating in their use of force than their enemies. The implication is that about 5% of our kills were civilians, while two-thirds or more of their kills were civilian, and that they killed civilians six times or more as often as we do. The further implication is that we kill civilians by accident, while they are doing so on purpose.
3. The numbers also show that there is still an active war in progress in Afghanistan in which law and order is not prevailing in large parts of the country.
The tricky part of a counterinsurgency operation is that the goal of the operation is not primarily to kill insurgents. Killing insurgents is a means to an end. The goal is to reduce the number and impact of insurgent attacks. In this respect, the mission is failing. Taliban military impact is increasing about five years later, rather than decreasing, and the opium trade is also flourishing. Some Republican big wigs have been quoted saying that there may need to be a political solution in Afghanistan that involves the Taliban in government. This isn't simply caving to terrorists, this is the reality of how insurgencies are ended and the Republicans shouldn't be chastized for being more aware of this fact in Afghanistan than they are in Iraq.
This doesn't mean that the war in Afghanistan hasn't been, on the whole, a success, or that it isn't worth continuing.
While the primary goal of the Afghan war, which was to destroy the leadership group behind the 9-11 attack, was not accomplished by the Afghan war, as this group fled to Pakistan, getting the Taliban out of power was not a bad thing. The Taliban regime was rightly despised worldwide, which is one of the main reasons that the U.S. was able to commence the war in Afghanistan without significant international opposition. The replacement, while hardly what a Western utopian vision would hope for, is better than the Taliban, came about more smoothly, is more widely accepted as legitimate than the current regime in Iraq.
This is being accomplished with a foreign force almost an order of magnitude smaller than the one in Iraq. The U.S. share of the total coalition is also a little smaller on a percentage basis, than the U.S. share of the coalition in Iraq. This is true despite the fact that Iraq and Afghanistan are similar in both population and geographic expanse, despite the fact that they are both Islamic countries with non-Islamic foreign military forces keeping peace, and despite the fact that in both cases, an existing regime which was the de facto government of the country was completely deposed.