William Lind, a military historian, has a 4GW (4th generation warfare) viewpoint on the wars in Iraq and Afghanistan that is worth reading.
How to fight 4GW (part 2)
One of his major points: we lost these wars when we destroyed the Afghan and Iraqi states and turned them into a lawless mess. He maintains that it is very hard to rebuild a state once it is destroyed and we will leave well before these countries are stable states again (the implication: this would turn Iraq and Afghanistan into Lebanons). [John Robb's Weblog]