Why don't they just take the Russian offer and be done with it rather than wasting time around with other countries that have limited or nil political say in the region? With Russian offer, US can even take up the alternate route deal and pass it through CAR rather than through Pakistan, straight into Afghan heartland without having to worry about Taliban or Pakistani-backed "rogue elements". Millions of dollars worth of supplies could be safer moving from CAR rather than risk getting burnt down or blown up by terrorists in Pakistani territory.
This playing around of Russia by US is costing US troops most dearly.