The use of Unmanned Combat Aerial Vehicles (UCAV) or drones have in recent yearsbecome the modus operandi of US counterterrorism strategy to eliminate sought out terrorists.Since the initiation of systematic drone strikes in Pakistan 2004, their use has increased andalso expanded into other countries. In 2012 Yemen experienced equal levels of strikes asPakistan. Thirteen years have passed since the “war on terror” began and although Osama binLaden has been killed, al-Qaeda still prevails and might be expanding. This study examines apossible spread of al-Qaeda from Pakistan to Yemen, since the initiation of drone strikes, byprocess tracing. Building on the literature of al-Qaeda, counterterrorism and UCAV, the aimhas been to analyze drone strikes affect on terrorism by tracing al-Qaeda’s development.Findings suggest there are indications of a spread from al-Qaeda in Pakistan to Yemen,although further research is required to confirm uncertainties in the material.