"In the last six weeks, a resurgent Taliban has surprised the Americans with the ferocity of its annual spring offensive and set some officials here to worrying that the United States might become tied down in a prolonged battle as control slips away from the central government — in favor of the movement that harbored Al Qaeda before 2001. And the number of American troops has quietly risen, not fallen. "Afghanistan is the sleeper crisis of this summer," says John J. Hamre, who was deputy defense secretary from 1997 to 1999."