Petraeus: If Obama says out, we go out

Charlie (paraphrased): Would you still order withdrawal if the commanders advised against it?
Obama: Because the commander-in-chief sets the mission, Charlie. That's not the role of the generals. (link)

[Petraeus] added that the feasibility of withdrawing U.S. troops in 16 months would depend on conditions that could not be forecast with much certainty.

“It depends on the conditions, depends on the mission set, depends on the — the enemy,” (link, emphasis mine.)