Skip to main content

Chemical Weapons: Status of Forensic Technologies and Challenges to Source Attribution

GAO-23-105439 Published: Sep 12, 2023. Publicly Released: Sep 12, 2023.
Jump To:

Fast Facts

Despite an international ban on their use, chemical weapons have been used over the past 10 years in assassinations and on civilian populations. When a chemical weapon is used, investigators may use forensic technologies to detect that it was used, identify the chemical, and help attribute it to a likely source.

Challenges to such investigations include small or degraded samples. These can result if investigators can't reach a site soon enough after an attack, or if it takes a long time to get samples to a lab.

We present 6 policy options to help decision makers address this and other challenges.

Some of the challenges of chemical analysis

A three-window infographic depicting common challenges faced during chemical analysis, including small, dilute, and degraded samples.

Skip to Highlights


What GAO Found

When a chemical weapon is used, investigators may use forensic technologies to detect that it was used, identify the chemical, and help attribute it to a likely source. Most technologies for chemical identification are mature. Some technologies for attributing chemical agents based on chemical analyses are under development. For example, a wide variety of laboratory-based and fieldable instruments for chemical identification are in commercial use. Investigators also use data from these instruments to help attribute chemicals to their potential sources, but there are limits to the information existing technologies can provide.

Key technologies to identify and attribute chemical weapons to a likely source

Technology Information it provides
Chromatography (Gas or Liquid) Separates and identifies chemicals in a sample mixture. Mature for identification of chemical agents, can inform attribution.
Nuclear Magnetic Resonance Spectroscopy Determines arrangement of atoms in a molecule. Mature for identification of chemical agents, developing for complex mixtures. Can inform attribution.
Mass Spectrometry Measures mass-to-charge ratios to identify chemicals in a mixture. Mature for identification of chemical agents, can inform attribution.
Impurity Profiling Identifies key impurities to link samples to production process or precursor. In development for attribution.
Isotope Ratio Methods Measures ratio of stable isotopes in a sample to link to a precursor. In development for attribution.

Source: GAO. | GAO-23-105439

GAO found several challenges that can hinder identification and attribution of chemical agents, including the following:

  • Poor samples: In some instances, investigators cannot obtain useful chemical information because samples are too small, dilute, or degraded.
  • Limited reference data: Generally, chemical identification methods rely on comparison to data from known chemicals, called reference data. However, reference data can be limited because they are resource intensive to collect, analyze, and archive. Additionally, reference data may be challenging to use in some instances, such as if they were developed using different experimental methods or stored in an incompatible format.
  • Lack of information sharing: Controls on information sharing are needed for national security concerns but can hinder collaboration among researchers in developing technologies and improving understanding of chemicals and their sources.
  • Limited coordination: Entities may not be aware of individual and laboratory expertise that could assist with identifying a chemical agent or its source. Researchers may unknowingly duplicate work, and opportunities to strengthen capabilities may be missed.

GAO identified six high-level policy options in response to these challenges. These policy options are provided to inform policymakers of potential actions to address the challenges identified in this technology assessment. They identify possible actions by policymakers, which include Congress, federal agencies, state and local governments, academic and research institutions, and industry.

Policy options to address challenges that hinder identification and attribution of chemical agents

Policy Option Opportunities Considerations
Develop technology to aid with sampling
(report p. 35)
Policymakers could encourage development of technologies that allow more rapid sample analysis or that slow sample degradation.
  • Could reduce likelihood of degradation by shortening time between sampling and analysis.
  • May reduce cost of analysis by minimizing the number of chemical signatures generated by sample degradation.
  • Small market size for certain instrumentation may limit industry interest in developing new technologies.
  • Testing of new technologies can be challenging due to the toxicity and reactivity of chemical agents.
Study known threats
(report p. 36)
Policymakers could advance scientific knowledge on known chemical agents and threats.
  • Could support a faster response to an event and faster attribution to a source.
  • Could ensure that the U.S. has the appropriate workforce, capabilities, knowledge, and facilities to respond effectively to chemical incidents.
  • In some cases, additional knowledge is unlikely to help identify a chemical (e.g., due to highly degraded samples) or attribute it to its source (e.g., when there are many possible production processes for a given chemical agent).
  • Building the necessary body of knowledge could be resource intensive.
Further anticipate emerging threats
(report p. 37)
Federal policymakers could foster development of technologies and approaches that help anticipate emerging chemical threats.
  • Could deter use of chemical agents and support a faster response in the event of use.
  • Emerging chemical threat assessment and characterization technologies could better prepare U.S. government entities and international partners for the unexpected.
  • A vast number of chemicals are potential emerging threats, and efforts would require careful prioritization.
  • Computational approaches would require security considerations to protect potentially classified chemicals.
Standardize data
(report p. 37)
Policymakers could encourage standardization of future data collection and support efforts to modernize legacy data on chemical threats.
  • Could ensure that computational methods work on data from different sources, maximizing efficiency and potential insights.
  • Modernized legacy data may provide insights that are otherwise expensive or difficult to acquire.
  • Consensus on standard operating procedures may be difficult to achieve.
  • Legacy data may be challenging to use in certain circumstances, such as due to changes in experimental design, instrumentation, and analytical techniques over time.
Share information
(report p. 38)
Federal and international policymakers could facilitate information sharing to increase collaboration on chemical agent forensic analyses.
  • Quickly making classification decisions about new and emerging information could improve appropriate research collaboration and information exchange.
  • Increased understanding of classification guidance could improve handling of classified information and allow researchers to more confidently know what information can be shared.
  • Classification systems are complex, and creating tools to assist in navigating them could be challenging.
  • Agencies need to balance facilitating additional information sharing with protecting information critical to national security.
Coordinate on chemical attribution
(report p. 40)
Federal and international policymakers could encourage increased coordination between entities involved in chemical attribution.
  • Clear roles and responsibilities could enable each entity to quickly execute its mission in response to a chemical incident.
  • Collective development of robust methods and capabilities could increase international confidence in findings.
  • Federal agencies often have different goals and requirements, so efficiencies may be limited, even with increased coordination.
  • Coordination activities with multi agency participation could divert resources away from other tasks.

Source: GAO. | GAO-23-105439

Why GAO Did This Study

Despite the Chemical Weapons Convention's ban on their use, chemical weapons have been used in the past decade in assassinations and on civilian populations. To identify the use of a chemical weapon and then attribute that weapon back to its source, researchers rely on several technologies for chemical analysis. Chemical analysis is one piece of an overall chemical weapon investigation.

This report discusses (1) the status of key technologies available to identify a chemical agent or its source, including their strengths and limitations; (2) challenges researchers and investigators face in trying to identify a chemical agent or its source; and (3) policy options that may help address the challenges of using key technologies to identify a chemical agent and its source.

To conduct this technology assessment, GAO reviewed key reports and scientific literature; interviewed government, intergovernmental, and academic representatives; conducted site visits; and convened two meetings of experts with the assistance of the National Academies of Sciences, Engineering, and Medicine. GAO is identifying policy options in this report.

For more information, contact Karen Howard at (202) 512-6888 or

Full Report

Office of Public Affairs


Chemical agentsChemical analysisChemical incidentsChemical informationChemical weaponsInformation sharingNew technologiesChemicalsWeaponsScientists