Could I make one quick comment?
This whole idea of at what stage people are open to negotiation is very important. It's been very frustrating to my group, who has been calling for this negotiation for years and who knows the Taliban were open to it at various times. And of course you're right, that as they go from victory to victory they may become less open to it.
To me, this is an argument for acting quickly, for acting now, before there is no opportunity at all.