The Taliban has claimed responsibility for a helicopter crash  on Saturday, which killed 30 American troops in the deadliest day ever for U.S. forces in Afghanistan. The attack took place in the Tangi Valley  of Wardak Province, to the west of Kabul, and illustrates how the insurgency is growing from its traditional strongholds and edging toward the capital city. Christine Fair, assistant professor at the Center for Peace and Security Studies at Georgetown University, discusses the insurgency in Afghanistan and its effect on U.S. strategy.