Tens of thousands of fresh American troops are now on the move in Afghanistan, led by a new commander and armed with a counterinsurgency plan that builds on the lessons of Iraq. But can U.S. forces succeed in a land long known as the “graveyard of empires”? FRONTLINE producers Martin Smith (Beyond Baghdad, Return of the Taliban) and Marcela Gaviria (In Search of Al Qaeda, The War Briefing) once ag