Karzai fought beside US Special Forces and was even wounded in a friendly fire incident that killed 2 green berets.
The fact of the matter is he is hedging. Obama is weak and has made the US an uncertain ally. Obama even tried to poison Karzai's political waters as soon as the former was sworn in by painting Karzai as worthy of removal. No word ever came forth about who would replace Karzai and since then we've seen how much Obama doesn't consider such things. A-stan could not compete against P-stan which supplies and trains the Taliban.
Obama has also poisoned our place in Iraq by bungling the SOFA negotiations forcing US troops out by year's end. Iraq is sandwiched between Syria and Iran with the Mahdi militia still active the Iraqis have made noises about supporting Assad's suppression of protesters. Think about that for a moment.
Iraq is overwhelmingly Sunni. In Syria Sunnis are also the majority but they are ruled by the 12% Alawite minority and Assad's government is Ba'athist, just as Saddam's was. The Iraqi's have no reason to back Assad other than they fear for their future and are making the best deal they can.
Mail your complaints to 1600 Pennsylvania Ave, Washington DC.