GAO

United States General Accounting Office

Testimony

Before the Subcommittee on National Security, Veterans 

Affairs, and International Relations, Committee on 

Government Reform, House of Representatives

For Release on Delivery 

at 10:30 a.m., EDT

Wednesday,

October 20, 1999 

COMBATING TERRORISM 

Observations on the Threat 

of Chemical and Biological 

Terrorism 

Statement of Henry L. Hinton, Jr., Assistant Comptroller 

General, National Security and International Affairs 

Division 

GAO/T-NSIAD-00-50

Page 1 GAO/T-NSIAD-00-50

Mr. Chairman and Members of the Subcommittee:

I am pleased to be here to discuss our report, Combating Terrorism: Need 

for Comprehensive Threat and Risk Assessments of Chemical and 

Biological Attacks (GAO/NSIAD-99-163, Sept. 7, 1999), issued last month to 

you, the Chairman and the Ranking Minority Member of the Senate 

Veterans’ Affairs Committee, and the Ranking Minority Member of the 

House Armed Services Committee. My testimony today summarizes the 

two principal messages of that report. First, it discusses the ease or 

difficulty for a terrorist to create mass casualties (defined as at least 1,000 

deaths or illnesses) by making and using chemical or biological agents 

without the assistance of a state-sponsored program. Second, it addresses 

the need to use intelligence estimates and risk assessments to better guide 

and prioritize appropriate countermeasures and programs. 

Because of the technical nature of the topic, we consulted numerous 

experts in the course of our work. For example, we obtained from 

intelligence agencies, the Federal Bureau of Investigation (FBI), military 

medical experts, and others lists of specific chemical and biological agents 

that might be used by terrorists. Experts formerly with U.S. and foreign 

government warfare programs provided detailed information on the 

production, weaponization, and delivery of chemical and biological agents. 

In addition, we interviewed experts in the fields of science, medicine, law 

enforcement, intelligence, and terrorism. We spoke with and obtained 

documentation from a number of federal agencies, including the U.S. Army 

Medical Research Institute of Infectious Diseases, the Centers for Disease 

Control and Prevention, the U.S. Army Soldier and Biological Chemical 

Command, and the Defense Threat Reduction Agency. We also analyzed 

manuals, handbooks, texts, reports, and studies on infectious diseases and 

on biological and chemical casualties.

Summary According to the experts we consulted, in most cases terrorists would have 

to overcome significant technical and operational challenges to 

successfully make and release chemical or biological agents of sufficient 

quality and quantity to kill or injure large numbers of people without 

substantial assistance from a state sponsor. With the exception of toxic 

industrial chemicals such as chlorine, specialized knowledge is required in 

the manufacturing process and in improvising an effective delivery device 

for most chemical and nearly all biological agents that could be used in 

terrorist attacks. Moreover, some of the required components of chemical 

agents and highly infective strains of biological agents are difficult to 
Page 2 GAO/T-NSIAD-00-50

obtain. Finally, terrorists may have to overcome other obstacles for a 

successful attack, such as unfavorable environmental conditions and 

personal safety risks. 

The President’s fiscal year 2000 budget proposes $10 billion for 

counterterrorism programs—an increase of more than $3 billion over the 

requested funding of $6.7 billion for fiscal year 1999. To assess whether the 

government is spending appropriate levels on counterterrorism and 

spending these funds on the most appropriate programs, policymakers 

need the best estimates of the specific threats the U.S. faces. The 

intelligence community has recently produced estimates of the foreignorigin terrorist threat involving chemical and biological weapons. However, 

the intelligence community has not produced comparable estimates of the 

domestic threat. In our report we recommended that the FBI prepare these 

estimates and use them in a national-level risk assessment that can be used 

to identify and prioritize the most effective programs to combat terrorism. 

The FBI agreed. 

Production and 

Delivery of Chemical 

and Biological Agents 

Generally Requires 

Specialized Knowledge 

Terrorists face serious technical and operational challenges at different 

stages of the process of producing and delivering most chemical and all 

biological agents. The Special Assistant to the Director of Central 

Intelligence for Nonproliferation testified in March 1999 that “the 

preparation and effective use of BW [biological weapons] by both 

potentially hostile states and by non-state actors, including terrorists, is 

harder than some popular literature seems to suggest.”1

 We agree. A 

number of obstacles exist for terrorists. Figure 1 shows the stages involved 

in making and using chemical or biological agents. It also illustrates some 

of the other impediments that terrorists may have to overcome such as 

obtaining source materials, risks to the terrorists, and environmental 

challenges. 

1

Unclassified statement on the worldwide biological warfare threat to the House Permanent 

Select Committee on Intelligence, March 3, 1999.
Page 3 GAO/T-NSIAD-00-50

Figure 1: Stages and Obstacles for Chemical and Biological Terrorism

Source: GAO, on the basis of analysis of technical data and discussions with chemical and biological 

warfare experts.

Some chemical agents are commercially available and require little 

sophistication or expertise to obtain or use, but other chemical agents are 

technically challenging to make and deliver. Toxic industrial chemicals 

such as chlorine, phosgene, and hydrogen cyanide are used in commercial 

manufacturing and could be easily acquired and adapted as terrorist 

weapons. In contrast, most chemical nerve agents such as tabun (GA), 

sarin (GB), soman (GD), and VX are difficult to produce. To begin with, 

developing nerve agents requires the synthesis of multiple chemicals that, 

according to the experts we consulted, are very difficult to obtain in large 

quantities due to the provisions of the 1993 Chemical Weapons Convention, 

which has been in force since April 1997. In addition, a 1993 Office of 

Technology Assessment report on the technologies underlying weapons of 

mass destruction indicated that some steps in the production process of 

these nerve agents are difficult and hazardous. For example, although 

tabun is one of the easier chemical agents to make, containment of the 

highly toxic hydrogen cyanide gas that is produced during the process is a 
Page 4 GAO/T-NSIAD-00-50

technical challenge. In general, production of chemical nerve agents could 

be technically unfeasible for terrorists without a sophisticated laboratory 

infrastructure because their production requires the use of high 

temperatures and generates corrosive and dangerous by-products. On the 

other hand, chemical blister agents such as sulfur mustard, nitrogen 

mustard, and lewisite can be manufactured with little to moderate 

difficulty; but again, according to experts, purchasing large quantities of 

certain chemicals needed to make blister agents is difficult due to the 

Chemical Weapons Convention. Even if chemical agents can be produced 

successfully, they must be released effectively as a vapor, or aerosol, for 

inhalation exposure, or they need to be in a spray of large droplets or liquid 

for skin penetration. To serve as terrorist weapons, chemical agents require 

high toxicity and volatility (tendency of a chemical to vaporize), and need 

to maintain their strength during storage and release. 

Causing mass casualties with biological agents also presents extraordinary 

technical and operational challenges for terrorists without the assistance of 

a state-sponsored program. For example, highly infectious seed stock for 

nearly all biological agents is difficult to obtain, particularly since controls 

over the stocks have improved. The only known sources of the smallpox 

virus, for example, are within government-controlled facilities in the United 

States and Russia. Ricin, a biological toxin, is easy to obtain and produce 

but requires such large quantities to cause mass casualties that the risk of 

arousing suspicion or detection prior to dissemination would be great. 

Although most biological agents are easy to grow if the seed stock can be 

obtained, they are difficult to process into a lethal form and successfully 

deliver to achieve large scale casualties. Processing biological agents into 

the right particle size and delivering them effectively requires expertise in a 

wide range of scientific disciplines. Since the most effective way to deliver 

a biological agent is by aerosol (to allow the simultaneous respiratory 

infection of a large number of people), the particles need to be small 

enough to reach the small air sacs in the lungs and bypass the body’s 

natural filtering and defense mechanisms. Terrorists can try to process 

biological agents into liquid or dry forms for release, but both forms pose 

difficult technical challenges. Experts told us that although liquid agents 

are easy to produce, it is difficult to effectively deliver them in the right 

particle size without reducing the strength of the mixture. Further, a liquid 

agent requires larger quantities, which can increase the possibility of 

raising suspicion and detection. Dry biological agents are easier to deliver, 

but they are more difficult to manufacture than liquid agents, are less 

stable, and are dangerous to work with. Other important technical hurdles 
Page 5 GAO/T-NSIAD-00-50

include obtaining the right equipment to generate properly sized aerosols, 

calculating the correct output rate (i.e., speed at which the equipment 

operates), and having the required liquid composition. 

Terrorists have additional hurdles to overcome. For example, outdoor 

delivery of chemical and biological agents can be disrupted by 

environmental (e.g., pollution) and meteorological (e.g., sun, rain, mist, and 

wind) conditions. Once released, an aerosol cloud gradually dissipates over 

time and as a result of exposure to oxygen, pollutants, and ultraviolet rays. 

If wind conditions are too erratic or strong, the agent might dissipate too 

rapidly or fail to reach the desired area. Indoor dissemination of an agent 

could be affected by the air exchange rate of the building. In addition, 

terrorists risk capture and personal safety in acquiring and processing 

materials, disposing byproducts, and releasing the agent. Many agents are 

dangerous to handle. In some cases the lack of an effective vaccine, 

antibiotic/antiviral treatment, or antidote poses the same risk to the 

terrorist as it does to a targeted population. 

National-Level 

Assessment of the Risk 

of Chemical and 

Biological Terrorism Is 

Needed to Focus 

Resources 

A national-level assessment of the risk of chemical and biological 

terrorism, based on analyses of both the foreign-and domestic-origin 

threats, could help determine the requirements and priorities for 

combating terrorism and target resources where most needed. Much of the 

intelligence information that can be incorporated into a national-level risk 

assessment already exists. The U.S. foreign intelligence community has 

issued classified National Intelligence Estimates and Intelligence 

Community Assessments that discuss the foreign-origin chemical and 

biological terrorist threat in some detail. These intelligence assessments 

identify the agents that would more likely be used by foreign-origin 

terrorists. 

The FBI is responsible for assessing domestic-origin threats. However, FBI 

analysts’ judgments concerning the more likely chemical and biological 

agents that may be used by domestic-origin terrorists have not been 

captured in a formal assessment. The FBI has not specified or ranked 

individual chemical or biological agents as threats, but instead ranked 

groups of agents according to the likelihood that a category of chemical or 

biological agent would be used. The FBI analysis was based on law 

enforcement cases where chemical or biological agents were used or their 

use was threatened, including hoaxes. The FBI’s categories are:
Page 6 GAO/T-NSIAD-00-50

• Biological toxins: any toxic substance of natural origin produced by an 

animal or plant. An example of a toxin is ricin, a poisonous protein 

extracted from castor beans. (Ricin, due in part to the ton quantities 

required to cause mass casualties, is more appropriate for attacking 

individuals or small numbers of people and is not generally considered 

to be useful as a mass casualty weapon.) 

• Toxic industrial chemicals: chemicals developed or manufactured for 

use in industrial operations such as manufacturing solvents, pesticides, 

and dyes. These chemicals are not primarily manufactured for the 

purpose of producing human casualties. Chlorine, phosgene, and 

hydrogen cyanide are industrial chemicals that have also been used as 

chemical warfare agents.

• Biological pathogens: any organism (usually living) such as a bacteria or 

virus capable of causing serious disease or death. Anthrax is an example 

of a bacterial pathogen. 

• Chemical agents: a chemical substance that is intended for use in 

military operations to kill, seriously injure, or incapacitate people. 

Excluded from consideration are riot control agents and smoke and 

flame materials. Two examples of chemical agents are sarin (nerve 

agent) and mustard gas (blister agent).

By combining an FBI estimate of the domestic-origin threat with existing 

intelligence estimates and assessments of the foreign-origin threat, analysts 

could provide policymakers with a better understanding of the threat from 

terrorists’ use of chemical or biological weapons. A national-level risk 

assessment based in part on the threat estimates would better enable 

federal agencies to establish soundly defined program requirements and 

prioritize and focus the nation’s investments to combat terrorism. For 

example, in March 1999 we testified2

 that the Department of Health and 

Human Services is establishing a national pharmaceutical and vaccine 

stockpile to prepare medical responses for possible terrorist use of 

chemical or biological weapons. We pointed out that the Department’s 

effort was initiated without the benefit of a sound threat and risk 

assessment process. We also found that some of the items the Department 

plans to procure do not match intelligence agencies’ judgments of the more 

likely chemical and biological agents that terrorists might use and seem to 

be based on worst-case scenarios. We questioned whether stockpiling for 

the items listed in the Department’s plan was the best approach for 

2

Combating Terrorism: Observations on Biological Terrorism and Public Health Initiatives

(GAO/T-NSIAD-99-112, Mar. 16, 1999).
Page 7 GAO/T-NSIAD-00-50

investing in medical preparedness. A sound threat and risk assessment 

could provide a cohesive roadmap to justify and target spending for 

medical and other countermeasures to deal with a chemical or biological 

terrorist threat. We recommended that the FBI sponsor a national-level 

threat and risk assessment, and the FBI agreed to do so.

Mr. Chairman, Members of the Subcommittee, that concludes my prepared 

remarks. I would be happy to answer any questions you may have.

Letr
Page 8 GAO/T-NSIAD-00-50

Related GAO Products

Combating Terrorism: Need for Comprehensive Threat and Risk 

Assessments of Chemical and Biological Attacks (GAO/NSIAD-99-163, 

Sept. 7, 1999).

Combating Terrorism: Observations on Growth in Federal Programs

(GAO/T-NSIAD-99-181, June 9, 1999).

Combating Terrorism: Analysis of Potential Emergency Response 

Equipment and Sustainment Costs (GAO/NSIAD-99-151, June 9, 1999).

Combating Terrorism: Issues to Be Resolved to Improve Counterterrorist 

Operations (GAO/NSIAD-99-135, May 13, 1999).

Combating Terrorism: Observations on Biological Terrorism and Public 

Health Initiatives (GAO/T-NSIAD-99-112, Mar. 16, 1999).

Combating Terrorism: Observations on Federal Spending to Combat 

Terrorism (GAO/T-NSIAD/GGD-99-107, Mar. 11, 1999).

Combating Terrorism: FBI’s Use of Federal Funds for CounterterrorismRelated Activities (FYs 1995-98) (GAO/GGD-99-7, Nov. 20, 1998).

Combating Terrorism: Opportunities to Improve Domestic Preparedness 

Program Focus and Efficiency (GAO/NSIAD-99-3, Nov. 12, 1998).

Combating Terrorism: Observations on the Nunn-Lugar-Domenici Domestic 

Preparedness Program (GAO/T-NSIAD-99-16, Oct. 2, 1998).

Combating Terrorism: Observations on Crosscutting Issues

(GAO/T-NSIAD-98-164, Apr. 23, 1998).

Combating Terrorism: Threat and Risk Assessments Can Help Prioritize 

and Target Program Investments (GAO/NSIAD-98-74, Apr. 9, 1998).

Combating Terrorism: Spending on Governmentwide Programs Requires 

Better Management and Coordination (GAO/NSIAD-98-39, Dec. 1, 1997).
Related GAO Products

Page 9 GAO/T-NSIAD-00-50

Combating Terrorism: Federal Agencies’ Efforts to Implement National 

Policy and Strategy (GAO/NSIAD-97-254, Sept. 26, 1997).

Chemical Weapons Stockpile: Changes Needed in the Management 

Structure of Emergency Preparedness Program (GAO/NSIAD-97-91, 

June 11, 1997).

(702025) Letr

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