Although WMD technologies are well understood, there have been few examples of their use by terrorists. The reason is simple: Conventional technologies such as nail bombs and explosives are easier, cheaper, and can even be more lethal. The sophisticated 1995 attack on the Tokyo subway with sarin killed 13 people, while the simpler 2005 explosives attack on the London subway killed 52 people.10
Although WMD technologies are well understood, there have been few examples of their use by terrorists. The reason is simple: Conventional explosives are easier, cheaper, and can be more lethal.