Every nation seeks its own destiny, consciously or unconsciously We cannot change that about Afghanistan; we can only interfere. Certainly, we can influence the course of a nation - for better or for worse - but that influence is equivalent to how a drought, or a flood, or an epidemic might affect a nation's arc. It is temporary - perhaps tangential - but nonetheless, single element in the otherwise unpredictability of peoples. No nation knows where it will be 100 years from now, including the U.S. Each nation will be affected by natural and man-made disasters, by great and terrible citizens of its own, by time.
Afghanistan is like a large elephant; our soldiers are like fleas on its back. They will make little difference in that elephant's course. Many will be thrown and end up with broken arms and legs; many more will be crushed.
In the end, America's politicians - the president, et al - will call our boys home. And they will begin a dangerous dismount, even as that elephant continues his jaunt across the Afghan plains. (He will not stop.) Still more young Americans will die while getting off.
Afghanistan's elephant has been running for a thousand years. America's elephant has been running for half as long; it runs a lot faster. It could be that the Afghan elephant will run for another thousand years. He may be running even after America's elephant has died.