In a right-wing cult classic movie of the 1980's,
Red Dawn, a Cuban-Russian coalition waged a counter-insurgency (COIN) war against the American people.
Because between them, they did not have enough troops to effectively occupy America, they attempted to make up the difference with air strikes. The only realistic element in the movie's scenario was that the would-be Russian and Cuban occupiers were ultimately unsuccessful.
That's what Obama's trying to do with Bush's legacy in Afghanistan.
Obama simply cannot accomplish anything tangible in Afghanistan using a fraction of the number of troops the Russians used decades before when their COIN effort ended in bloody and costly failure. He cannot get substantially additional troops from European allies. He certainly can't make up the difference in American troops. In light of our over-extended military forces, not to mention our straining economy, it should be apparent that there is not that much more "there" to throw at the Afghani insurgents.
Clearly, the use of air power to replace boots on the ground encourages the use of bombs, missiles and other attacks by war planes that directly increase the risk to civilians. In counterinsurgency operations, from a strictly military standpoint the excessive killing of civilians is counterproductive. It increases opposition to the forces who employ the weaponry that unnecessarily places civilian lives at risk.
If we can't do it right with enough ground troops, why are we - and how long will we persist in - trying to do it ineffectively? Obama's Afghanistan policy is unsustainable.