The Russians were there also at the behest of the then Afghan gov't so I'm not sure how much genuine legitimacy this bestows.
I'd like to think the Bush administration has been trying to capture Bin Laden since Sept 12th 2001.
During the first world war snipers always aimed at officers first, to the extent both Britain and Germany complained at a very high level about each other's practices.
Despite tremendous success in wiping out each other's officer corp on a near daily basis it made not an iota of difference to the war itself. New officers were appointed and the war went on.
The same is now true today. The only good thing that comes out of killing Taliban leaders is the bragging rights in the paper the next day. In terms of defeating the enemy it is meaningless.