From a May 19 Stratfor report:

It is essential to understand that the Taliban were not destroyed in the 2001 invasion. Under pressure from the Northern Alliance forces recruited by the United States, and by U.S. air power, Taliban forces declined combat in the cities, where they would have been decimated. They withdrew and dispersed, regrouping in isolated villages and across the Pakistani border. Then they systematically returned -- each year, increasing their tempo of operations and, each year, extending their reach. As the combat season begins every spring, Taliban activities increase. So it follows that, in the fifth spring since Kabul's fall, the intensity of fighting should be the greatest yet.

As I have said many times before and will probably say many times yet before our Afghan adventure is over: taking Afghanistan is the easy part. Holding it? Now that is something else altogether.

Nota bene: It occurs to me that my reference to Dr. Brydon may be a bit obscure historically. More about the doctor can be found here.