Yemen's military, backed by US drones, has launched a major offensive in Abyan province in the south. It aims to recapture large parts of the province under the control of fighters affiliated with al-Qaeda. So what does this fight in Yemen mean for al-Qaeda and the forces battling to defeat them, and how much has the group evolved in the years since the 9/11 attacks of 2001? Guests: Zaid Hamid, Phil Rees, Robin Simcox.