As a U.S. tank comes into view on a Ramadi street, three fighters in civilian clothes and keffiyeh headscarves aim their weapons and wait. They are from the insurgent group Al Qaeda in Iraq. "This is a message to America," one insurgent says to the camera. "Look at your might and power, yet you are unable to walk the streets of Ramadi, which belongs to the mujahideen." He turns back to the tank, which has paused a few blocks away. "I swear by almighty God we will destroy them."Through interviews and never-before-seen footage featuring insurgent leaders and their foot soldiers, U.S. military personnel and journalists, this FRONTLINE report, "The Insurgency," investigates the people who are fighting against U.S. and coalition forces in Iraq.