animals, or plants. Biological agents are typically found in nature, but it is possible that they can be changed to increase their ability to cause disease, make them resistant to current medicines, or to increase their ability to be spread into the environment. Biological agents in the hands of terrorists pose serious threats to states’ security because they can be easily spread through the air, through water, and through food. Biological agents can also be difficult to detect and often do not cause illness for several hours to several days. A prominent example of a bioterrorist attack on the United States is the September 2001 anthrax attacks. On September 18, 2001, several letters containing anthrax were sent to media outlets and the U.S. Congressional offices of Senator Thomas Daschle and Senator Patrick Leahy. Five Americans died from anthrax inhalation as a result of contact with the contaminated mail. While the 2001 anthrax attacks were relatively small-scale, the United States government has taken several steps since to 2001 to pass legislation and initiatives aimed at better protecting the United States against biological attacks, improving the United States’ public health system, and improving the United States ability to respond to biological attacks. The use of chemical weapons includes that by Aum Shinrikyo, a Japanese "new religious movement", which in 1995 carried out the Sarin gas attack on the Tokyo subway. Ian Davison, a British white supremacist and neo-Nazi who was arrested in 2009 for planning terrorist attacks involving ricin poison. In 2011 the United States government discovered information that terrorist groups were attempting to obtain large amounts of castor beans for weaponized ricin use. Agro-terrorism A subset of bioterrorism, agroterrorism refers to the deliberate introduction of an animal or plant disease for the purposes of generating fear, causing economic losses, or undermining social stability. The ultimate goal of agroterrorism in killing livestock and plants and contaminating food is to cause economic crises in the agricultural and food industries, social unrest, and loss of confidence in the government. Many experts believe that the United States’ agricultural sector and food supply are among the most vulnerable and least protected of all potential targets of attack, and they believe that terrorists have taken note of this. After American and allied forces overran some Al-Qaeda's refuges in caves in eastern Afghanistan in 2002, they found U.S. agricultural documents and Al-Qaeda training manuals on targeting agriculture among