Summary

The ease or difficulty for terrorists to cause mass casualties with an improvised chemical or biological weapon depends on the agent selected. Experts agree that toxic chemicals can cause mass casualties and require little if any expertise or sophisticated methods. Most chemical nerve agents, however, are technically challenging for terrorists to acquire, manufacture, and produce. Also, terrorists working outside a state-run laboratory would have to overcome extraordinary challenges to effectively and successfully weaponize and deliver a biological agent and cause mass casualties. Although the intelligence community has issued assessments that discuss foreign-origin and biological terrorist threats, including judgements about which chemical and biological agents would most likely be used, the FBI has yet to produce a formal written assessment of the most likely domestic-origin chemical and biological terrorist threats. GAO believes that a sound national-level risk assessment could provide a strategic guide to help shape, focus, and prioritize federal efforts to combat terrorism. Such an assessment would be done by a multidisciplinary team of experts on intelligence, terrorism, chemical and biological agents, weapons, law enforcement, and health and other experts. The team could (1) generate valid threat scenarios, (2) assess and prioritize scenario risk in terms of the likelihood and the severity of consequences, and (3) determine appropriate countermeasures or other programmatic responses.

GAO noted that: (1) chemical and biological experts and intelligence agency officials believe that the ease or difficulty for terrorists to cause mass casualties with an improvised chemical or biological weapon or device depends on the chemical or biological agent selected; (2) specialized knowledge would be needed to acquire the right biological agent or precursor chemicals, process the chemical or biological agent, improvise a weapon or device, and effectively disseminate the agent to cause mass casualities; (3) some virulent biological agents and precursor chemicals are difficult to obtain, and others are difficult to process or produce, especially in the quantities needed to cause mass casualities; (4) in addition, effective dissemination of chemical and biological agents can be disrupted by environmental and meteorological factors; (5) terrorists with less sophistication could make a chemical or biological weapon and disseminate agents, but these would be less likely to cause mass casualities; (6) preventive measures and medical treatments are available for some, but not all chemical and biological agents that might be used by terrorists; (7) the intelligence community has recently produced National Intelligence Estimates and other high-level analyses of the foreign-origin terrorist threat that include judgments about the more likely chemical and biological agents that would be used; (8) unlike the foreign-origin terrorist threat, the Federal Bureau of Investigation's (FBI) analysts' judgments concerning the more likely chemical and biological agents to be used by domestic-origin terrorists have not been captured in a formal, authoritative, written assessment; (9) moreover, a national-level risk assessment of potential chemical and biological terrorist incidents also has not been performed; (10) soundly performed risk assessments could help ensure that specific programs and related expenditures are justified and targeted according to the threat and risk of validated terrorist attack scenarios generated and assessed by a multidisciplinary team of experts; and (11) in the case of the Department of Health and Human Services national stockpile initiative, without valid threat and risk assessments, GAO questions whether stockpiling for the items and quantities discussed in the Department's plan is the best approach for investing in medical preparedness.