Why?

Can someone please tell me whywe still have Canadian soldiers in Afghanistan? What exactly have they done there in the last seven years that makes the death of four more brave men worthwhile?
The Torch writes:

Soldiers I've spoken with are not of one mind on this issue, and I wouldn't pretend to speak for them in such a situation. But many of them have expressed to me their frustration that the media and public pay attention only to the costs of the mission, and not to what Canadian blood and treasure is accomplishing in Kandahar.

And while I respect this sentiment, I still would like to know what our military has actually accomplished in Afghanistan.