More US troops. More casualties for the US and its allies. Surging Taliban violence. With all eyes in Afghanistan second presidential election this week, there's plenty of pressure on Washington to show results in a war that President Barack Obama has put at the center of his foreign policy.

Combat deaths are rising - the US toll is 779 and Britain's 201 - as polls show a softening of public backing for the eight-year war.

A generation ago, it would have been hard to imagine asking, say, General George S. Patton if casualties were making a US war effort unwinnable or not worth fighting.