section_path: Perpetrators
section_name: Perpetrators
paragraph_text: Perpetrators
  
  The perpetrators of acts of terrorism can be individuals, groups, or states. According to some definitions, clandestine or semi-clandestine state actors may carry out terrorist acts outside the framework of a state of war. The most common image of terrorism is that it is carried out by small and secretive cells, highly motivated to serve a particular cause and many of the most deadly operations in recent times, such as the September 11 attacks, the London underground bombing, 2008 Mumbai attacks and the 2002 Bali bombings were planned and carried out by a close clique, composed of close friends, family members and other strong social networks. These groups benefited from the free flow of information and efficient telecommunications to succeed where others had failed.
  
  Over the years, much research has been conducted to distill a terrorist profile to explain these individuals' actions through their psychology and socio-economic circumstances. Some specialists highlight the lack of evidence supporting the idea that terrorists are typically psychologically disturbed. The careful planning and detailed execution seen in many terrorist acts are not characteristics generally associated with mentally unstable individuals. Others, like Roderick Hindery, have sought to discern profiles in the propaganda tactics used by terrorists. Some security organizations designate these groups as violent non-state actors. A 2007 study by economist Alan B. Krueger found that terrorists were less likely to come from an impoverished background (28 percent versus 33 percent) and more likely to have at least a high-school education (47 percent versus 38 percent). Another analysis found only 16 percent of terrorists came from impoverished families, versus 30 percent of male Palestinians, and over 60 percent had gone beyond high school, versus 15 percent of the populace.
  
  To avoid detection, a terrorist will look, dress, and behave normally until executing the assigned mission. Some claim that attempts to profile terrorists based on personality, physical, or sociological traits are not useful. The physical and behavioral description of the terrorist could describe almost any normal person. The majority of terrorist attacks are carried out by military age men, aged 16 to 40.