“[My time at ACA] prepared me very well for the position that I took following that with the State Department, where I then implemented and helped to implement many of the policies that we tried to promote.”
– Peter Crail
Business Executive for National Security
June 2, 2022
Verifying the Chemical Weapons Ban: Missing Elements

Latest ACA Resources

Jonathan B. Tucker

The Chemical Weapons Convention (CWC), which bans the development, production, stockpiling, transfer, and use of chemical arms, is the first treaty to prohibit an entire category of “weapons of mass destruction” under strict international verification. Serving the dual goals of disarmament and nonproliferation, the CWC aims to eliminate existing chemical weapons stockpiles and production capacities and to prevent their acquisition in the future.

Because many toxic chemicals and their precursors are dual use, meaning that they have both peaceful and hostile applications, the CWC verification regime covers not only military facilities but also a large number of commercial chemical plants.[1]

Since the CWC entered into force on April 29, 1997, it has racked up some important accomplishments. More than 180 states already have signed and ratified the convention, an unparalleled number for an arms control treaty in such a short period, although a few suspected chemical weapons possessors remain outside the regime.[2] Six member states—Albania, India, Libya, Russia, South Korea, and the United States—have declared stockpiles of chemical weapons and are in the process of destroying them. Because of technical and political delays, only Albania is likely to meet the original CWC destruction deadline of 2007. The United States and Russia, the two largest possessors, will probably not finish the task until after the extended treaty deadline of 2012. In addition, 12 parties have declared a total of 65 former chemical weapons production facilities, all of which must be dismantled or converted to peaceful purposes.[3]

Overall, the complex verification regime for the CWC has operated fairly well, but several important gaps and limitations have become apparent during the first decade of implementation. If not corrected, these problems could impede the treaty’s ability to prevent the future proliferation of chemical weapons. The 10th anniversary of the CWC’s entry into force in April provides an opportune moment to begin addressing the gaps in its verification regime, although devising effective solutions will require vision and leadership on the part of the United States and other member states.

The CWC Verification Regime

CWC verification involves the continuous monitoring of chemical weapons stockpile destruction, as well as on-site inspections of commercial chemical plants to ensure that no further production of warfare agents or precursors occurs in the guise of chemical manufacturing for peaceful purposes.[4] Monitoring compliance with the treaty at the international level is the responsibility of a permanent multilateral agency, the Organization for the Prohibition of Chemical Weapons (OPCW), based in The Hague. The OPCW’s Technical Secretariat includes a verification division with an international corps of about 180 inspectors who travel to declared military and industrial sites around the world.

The fundamental challenge of CWC verification relates to the Janus-faced nature of chemical technology. When the negotiators of the CWC designed the treaty provisions prohibiting the development and production of chemical weapons, they had to find a way of dealing with the fact that many toxic chemicals and precursors used for military purposes also have legitimate peaceful applications. Moreover, because new synthetic compounds with toxic properties are continually being discovered, it was clear that any list of banned chemical warfare agents and precursors would rapidly become obsolete.

For this reason, the CWC negotiators decided to focus the basic prohibitions of the treaty on the purpose for which chemicals are developed and used. Article II of the treaty defines chemical weapons as “toxic chemicals and their precursors, except where intended for purposes not prohibited under this Convention, as long as the types and quantities are consistent with such purposes.” In addition, a toxic chemical is defined very broadly as “any chemical which through its chemical action on life processes can cause death, temporary incapacitation or permanent harm to humans or animals.”

As a result of these generic definitions, the basic prohibitions in Article I of the CWC apply to any toxic chemical whose development, production, stockpiling, or use is intended for hostile purposes, regardless of its origin or method of synthesis. This purpose-based approach, known in arms control literature as the “general purpose criterion,” was adapted from similar language in the 1972 Biological Weapons Convention. In addition to being comprehensive, the general purpose criterion enables the CWC to cover future scientific and technological developments. In principle, as soon as a new toxic chemical is developed or applied for hostile purposes, it automatically falls under the purview of the general purpose criterion.

As a practical matter, however, the OPCW international inspectorate cannot possibly monitor the entire universe of chemicals that might be misused. Instead, the CWC negotiators agreed on a verification system based on three “schedules,” or lists of toxic chemicals and their precursors that have been developed and manufactured in the past for military purposes. Schedule 1 consists of chemical warfare agents and precursors that have no significant commercial applications, although they may be synthesized in small quantities for scientific research, pharmaceutical development, or chemical defense. Schedule 2 lists toxic chemicals and precursors that have commercial applications in small quantities. Schedule 3 contains toxic chemicals and precursors that have commercial applications in large quantities. Facilities that manufacture “scheduled” chemicals at levels higher than specified quantitative thresholds must be declared and inspected on a routine basis. Moreover, the intrusiveness of the inspections is a function of the schedule on which a particular chemical is listed, so that facilities producing Schedule 1 chemicals receive the greatest scrutiny and those producing Schedule 3 chemicals the least.

The treaty negotiators decided to include in Schedule 1 only those toxic chemicals and precursors for which past weaponization or stockpiling was a known fact. For this reason, all of the listed agents, such as mustard, sarin, VX, and certain of their precursors, were already more than 20 years old when the CWC entered into force. Many of these “classical” agents are not obsolete and must continue to be monitored. Mustard gas, for example, was first synthesized in the nineteenth century but still remains a threat. Nevertheless, several next-generation agents and precursors not listed on the schedules pose significant risks to the treaty and hence warrant greater attention.

Chemicals of concern that remain outside the schedules include most members of the novichok family of binary nerve gases, which Soviet military chemists invented during the 1970s and 1980s.[5] Also unlisted in Schedule 1 are several chemicals designed to penetrate gas masks, as well as long-lasting incapacitants and “calmative” agents, such as the anesthetic fentanyl and related compounds, which both the United States and Russia have developed under the CWC’s exemption for “law enforcement, including domestic riot control.”[6] Another set of compounds of concern lies at the frontier of chemistry and biology, including toxins (toxic molecules produced by living organisms) and bioregulators (natural body chemicals that have potent effects on the nervous and immune systems). Only two such biochemical agents—the toxins ricin and saxitoxin—are listed on Schedule 1.

Because the CWC negotiators decided for practical reasons to use the schedules as the basis for determining which chemical industry facilities should be declared and routinely inspected, the prohibitions in the treaty are considerably broader than the mechanisms designed to verify them. Without this compromise, the monitoring regime would have been overly burdensome and costly to implement. Although the CWC negotiators devised an expedited process for amending the schedules to incorporate new toxic chemicals and precursors, member states have so far declined to use it. One reason for not adding the novichoks and their precursors to the schedules is that the Russian government has refused to acknowledge their development. In addition, several Western countries worry that listing these compounds would disclose their molecular structure and thereby facilitate their acquisition by state proliferators and terrorist groups.

More generally, the negotiators of the CWC understood that the schedules alone do not provide an adequate basis for verifying the nonproduction of chemical weapons. Wherever one chooses to draw the line in compiling the schedules, there will always be some toxic chemicals or precursors left outside that, if misused for hostile purposes, could pose a risk to the CWC.

To compensate for the fact that the noncomprehensive nature of the schedules limits the scope of the routine inspection regime, the negotiators introduced four measures into the CWC to help verify the general purpose criterion and prevent the emergence of safe harbors exempt from monitoring, where violators could develop novel chemical warfare agents not listed on the schedules and manufacture them secretly at undeclared facilities. This verification “safety net” consists of (1) a provision for routine inspections of “other” chemical production facilities that do not currently manufacture scheduled chemicals but may have the technical capability to do so; (2) the use of sampling and analysis during on-site inspections of chemical industry; (3) the right of any member state to request a challenge inspection of a suspect facility, declared or undeclared, on the territory of another state-party; and (4) the obligation on each state-party to create a national authority and pass domestic implementing legislation to monitor the general purpose criterion at the national level.

Unfortunately, the member states of the CWC have so far failed to make effective use of these four measures, leaving large holes in the verification safety net. The prevailing assumption among states-parties seems to be that if a toxic chemical or precursor is not listed on one of the three schedules, it does not pose a security threat. Yet, given the large number of unscheduled chemicals that could lend themselves to effective weaponization, the narrow scope of the routine verification regime risks creating false confidence in compliance, especially when one considers the impact of recent advances in chemical science and technology (see sidebar). As the OPCW’s Scientific Advisory Board noted in 2003, “[T]he number and types of unscheduled chemicals that could cause considerable harm, if they were misused for [chemical warfare] purposes, have expanded significantly. ... The inspection regime of the OPCW, perhaps with the exception of challenge inspection, would at this moment not be capable of detecting such a violation.”[7]

Coverage of “Other” Production Facilities

The primary focus of routine inspections of the chemical industry under the CWC is on declared production facilities that manufacture the dual-use chemicals listed on Schedules 2 or 3. In recent years, however, the advent of small, multipurpose chemical-production facilities has made the batch synthesis of organic (carbon-based) compounds more automated and flexible. Such multipurpose plants are potentially easier to divert to chemical weapons production than large, inflexible facilities that produce specific scheduled chemicals.[8] Thus, if the CWC verification regime is to remain effective, it must adapt to these technological changes by covering a broader range of chemical industry facilities, including plants that do not currently manufacture scheduled chemicals but have the capability to do so on a large scale.[9]

Part IX of the CWC Verification Annex defines other chemical production facilities (OCPFs) as plant sites that produce by synthesis more than 200 metric tons per year of discrete organic chemicals (DOCs) not listed in the schedules. This definition also encompasses one or more plants that manufacture more than 30 metric tons of an unscheduled DOC containing phosphorus, sulfur, or fluorine (PSF), which are common constituents of blister and nerve agents. These facilities must be declared, after which the OPCW Technical Secretariat selects a small fraction of them for inspection each year, using specially designed computer software that seeks to balance such factors as geographical distribution and the characteristics of the plant site and the activities performed there.

As of November 2006, 77 member states had declared a total of 5,225 OCPFs, or more than five times the number of declared facilities that produce Schedule 1, 2, and 3 chemicals.[10] Moreover, whereas most Schedule 2 facilities are unable to produce Schedule 1 chemicals, about 10 to 15 percent of OCPFs have flexible production equipment that is potentially capable of manufacturing chemical warfare agents or precursors, giving these plants a breakout potential that makes them highly relevant to the CWC.[11] In response, the OPCW Scientific Advisory Board has recommended increasing the number of inspections at OCPFs and improving the risk-assessment methodology to select those sites that pose the highest risk of misuse.[12] Of greatest concern are facilities that manufacture PSF chemicals, which may be structurally related to some well-known chemical warfare agents and precursors, as well as plants that incorporate multi-purpose production equipment and special ventilation systems to contain toxic fumes.

One way to increase the number of OCPF inspections with existing resources would be to reallocate more inspectors for this purpose. At present, the OPCW inspectorate devotes a disproportionate share of its efforts to monitoring the destruction of declared chemical weapons stockpiles. Because the CWC requires the continuous monitoring of the destruction process, inspectors must be stationed permanently at each destruction facility. In 2005, for example, the OPCW devoted a total of 15,519 inspector days to monitoring chemical weapons destruction at 13 sites, yet it spent only 1,379 days inspecting facilities that produce scheduled chemicals and 1,272 days inspecting OCPFs.[13] A better verification strategy would make greater use of remotely operated equipment, such as flow meters and closed-circuit television cameras, to monitor the destruction of chemical weapons while freeing up more trained personnel to inspect OCPFs.

Such a shift of human resources from monitoring chemical weapons destruction to inspecting OCPFs would offer several benefits for the effectiveness of the CWC as a nonproliferation tool. First, whereas facilities that manufacture scheduled chemicals are rare in developing countries, OCPFs exist throughout the developed and the developing world. Indeed, for reasons of market access, international chemical firms are increasingly building production plants in developing countries. For this reason, increasing the number of OCPF inspections would broaden the geographic scope of the CWC verification regime while reaffirming the key principle that the scope of the treaty is not limited to scheduled chemicals.

Nevertheless, the proposal to increase the number of OCPF inspections faces significant political obstacles. Some developing countries with chemical industries oppose the idea because they would have to bear a larger share of the verification burden. During the first CWC review conference in April 2003, Pakistan stated that an “[i]ncrease in emphasis on verification...of facilities producing relatively harmless [DOCs] should not be at the expense of higher risk Schedule 1, 2, and 3 chemicals listed in the Annex to the CWC.”[14] Convincing Pakistan and other developing countries to accept and allocate more resources for OCPF inspections might require a deal with Western industrialized states. To date, Western countries have made little effort to implement Article XI of the CWC, which calls for international cooperation among member states in the peaceful uses of chemistry. Because this provision is popular with developing countries, Western states might offer to fund suitable Article XI projects in exchange for an agreement to redeploy human and financial resources from monitoring chemical weapons destruction to conducting more inspections of OCPFs.

Sampling and Analysis at Chemical Industry Facilities

A second major gap in the CWC verification regime has been the lack of sampling and analysis during routine inspections of chemical industry sites, even though the technique has been used on a regular basis at chemical weapons destruction facilities to confirm the declared contents of munitions and bulk containers. Part VII of the CWC Verification Annex states clearly that sampling and analysis “shall be undertaken” for spot checks during routine inspections of Schedule 2 production facilities to confirm the absence of undeclared scheduled chemicals, yet sampling at such sites has occurred only rarely in practice. Although the United Kingdom has allowed OPCW personnel to take samples during Schedule 2 inspections and actively encouraged other states-parties to follow suit, several member countries have claimed (with no legal basis) that sampling at Schedule 2 plants is voluntary or may be performed only to resolve an anomaly that arises during an inspection. In fact, the CWC states that although sampling and analysis is voluntary at Schedule 3 plants and OCPFs, in keeping with the less-intrusive nature of such inspections, it is mandatory at Schedule 2 sites. To correct this problem, in July 2006 the OPCW launched an 18-month trial program to increase the use of on-site sampling and analysis during routine inspections of Schedule 2 facilities.[15]

CWC member states have approved two types of analytical equipment for on-site analyses. The primary device in use is a portable gas chromatograph/mass spectrometer, or GC-MS, which identifies a compound by comparing its mass spectrum, or molecular fingerprint, against a library of spectra of known compounds stored in an electronic database. The portable GC-MS has a number of drawbacks that have limited its use during routine inspections of chemical industry sites. Together with the sample preparation kit, fume hood, and shipping container, the device weighs 1,500 kilograms and occupies about one cubic meter of space. Because OPCW inspection teams often travel on a scheduled international flight to the point of entry and then by domestic airline to the inspection site, transporting the entire set of equipment is logistically complex and expensive.[16] Current sample preparation techniques for GC-MS are also difficult to carry out and require large volumes of solvents. Nevertheless, smaller, lighter GC-MS instruments are now available that are more easily transported and also have higher sensitivity. Indeed, it is time to review the entire set of approved equipment used by the OPCW inspectorate in light of the dramatic improvements in analytical science and technology that have occurred over the past decade.

Another reason for the limited use of sampling and analysis during routine inspections is that some representatives of the chemical industry believe that GC-MS is overly intrusive and could disclose proprietary information. For example, Garrity Baker, senior director for global affairs at the American Chemistry Council, a leading trade association, contends that the spectral analysis of a sample would reveal details of its composition and manufacturing process that could find their way into the hands of competitors. In fact, this fear appears to be exaggerated. The OPCW Technical Secretariat has processed vast amounts of confidential information without any significant breaches of its stringent classification procedures.[17] If the current trial period of sampling and analysis during routine inspections of Schedule 2 facilities proceeds smoothly, it should allay industry’s fears about the possible compromise of proprietary data and set a useful precedent. Although violators of the CWC would be unlikely to produce chemical warfare agents at Schedule 2 plants, which receive a relatively high level of scrutiny, more frequent sampling and analysis at these sites could open the way to the future use of this measure during inspections of high-risk OCPFs, where its contribution to verification would be much greater.

At present, however, lingering concerns about the potential for compromising confidential proprietary information have constrained the nature of on-site analysis at chemical industry facilities. Detailed rules for CWC implementation developed prior to the treaty’s entry into force and adopted in 1997 by the first conference of the states-parties limit the use of on-site analysis to verifying the presence or absence of undeclared scheduled chemicals, unless otherwise agreed in consultation with the facility representative.[18] To comply with these constraints, OPCW inspectors use a software package called AMDIS[19] that, when run in blinded mode, prevents the GC-MS operator from seeing and recording the raw data generated by the machine. Instead of identifying all of the compounds present in a sample, the blinded software compares the sample’s mass spectrum against the OPCW Central Analytical Database, which contains the spectra of some 2,000 scheduled chemicals and stable degradation products. The software package determines whether a match exists to a set probability. Thus, when AMDIS is run in blinded mode, it generates a list of scheduled chemicals in the sample whose spectra match those in the OPCW database, and any unscheduled chemicals that may be present will not be identified.

A major problem with restricting GC-MS analysis to scheduled chemicals and their stable degradation products is that a country that intended to violate the CWC would have a strong incentive to develop and produce an unscheduled agent in a bid to evade detection. In recognition of this gap in the verification regime, in 2003 the OPCW Scientific Advisory Board recommended expanding the spectral database for GC-MS to include data on certain unscheduled chemicals that have the potential to be used for warfare or terrorism, as well as other chemicals that are likely to be confused with scheduled chemicals.[20] Those spectra that are proliferation-sensitive could be classified as confidential and handled as such.

In addition to expanding the use of sampling and analysis during routine industry inspections, CWC member states should explore alternatives to the use of blinded analytical software for protecting commercial trade secrets. Conducting GC-MS analyses in the “unblinded,” or “open,” mode has always been an option, technically speaking, and may be to the advantage of the inspected state-party. In particular, analysis in open mode would permit the use of a larger database that contains the spectra of scheduled and unscheduled compounds, providing greater certainty in matching chemicals and avoiding inadvertent false-positive results that could implicate an innocent facility.[21]

Because the right of the inspected state-party to require the use of blinded analytical software during routine inspections is not stipulated in the CWC but was affirmed by the first conference of the states-parties, it should be possible to reverse this policy as part of the normal process of reviewing and refining treaty implementation in response to experience. Nevertheless, persuading states-parties to accept on-site analyses in open mode will be a political challenge. One way to reassure the chemical industry about the protection of trade secrets would be to require OPCW inspection teams to leave all samples and items containing sample residues, such as gas-chromatographic columns, at the inspected facility and to erase magnetic storage media before departing the site.

Sampling and analysis during inspections of chemical industry facilities is generally intended to take place on-site and to detect fairly high concentrations of the target compounds—raw materials, products, and intermediates—rather than trace quantities. Nevertheless, in cases where on-site analysis yields inconclusive results or an ambiguity that can be resolved only through the use of more sophisticated analytical techniques, the CWC provides that the sample should be split and sent to at least two reference laboratories for off-site analysis. Laboratories designated to serve this function must be certified by the OPCW and participate in regular proficiency tests.[22] Unfortunately, the use of off-site analysis has been seriously constrained by condition 18 of the U.S. Senate’s 1997 Executive Resolution on Ratification of the CWC, which precludes OPCW inspectors from removing chemical samples from U.S. territory.[23] Other member states, including India, have emulated the U.S. condition by including in their national legislation the right not to allow samples to be analyzed outside their own territory.

Despite these limitations, however, off-site analysis should be considered for use in cases where on-site analysis is inconclusive. Off-site analysis typically involves the use of multiple techniques without blinded software, giving more reliable results with trace quantities. In addition, the confirmation of an analytical finding by laboratories in different countries would greatly enhance its credibility. To safeguard proprietary information during off-site analyses, the OPCW has developed standard operating procedures that ensure the chain of custody of samples and protect confidential data. The main drawback of off-site analysis is that reference laboratories generally expect to be paid for their services, increasing inspection costs.

Challenge Inspections of Suspect Facilities

The third gap in the CWC verification regime is the failure of member states to make effective use of the challenge inspection mechanism. Article IX grants CWC states-parties the right to request a challenge inspection of any site, declared or undeclared, on the territory of another member state “for the sole purpose of clarifying and resolving any questions concerning possible non-compliance.” The CWC negotiators intended that challenge inspections would capture clandestine development and production facilities, chemical weapons stockpiles, and prohibited activities that a cheater has deliberately not declared and are hence not subject to routine inspection. For example, if a member state acquired a chemical weapons stockpile by producing an unscheduled toxic chemical at an undeclared facility, a challenge inspection would provide the only way of detecting this violation.

Given the dramatic scientific and technological changes that are transforming the global chemical industry, one would expect that challenge inspections would play an increasingly important role in CWC verification. Yet, despite the existence of compliance concerns and ambiguities, no state-party has made use of this key verification tool. For instance, the United States has publicly accused China, Iran, Russia, and Sudan of violating the CWC, yet it has not provided specific evidence nor pursued these allegations through challenge inspections, thereby weakening the treaty.[24]

Disincentives to launching a challenge inspection include the possible need to disclose sensitive intelligence information to justify the request; the risk that the inspection will not find “smoking gun” evidence of a treaty violation, particularly if the precise location of the prohibited activity is unknown; the ability of an accused state to retaliate by requesting a challenge inspection of a sensitive facility in the initiating country; and the possibility that the OPCW Executive Council will block a challenge request that it judges it to be frivolous or abusive.[25] Finally, because requesting a challenge inspection may be perceived as a confrontational act, increasing political tensions with the accused country, member states may prefer to pursue their compliance concerns through confidential bilateral channels. The longer the challenge mechanism remains unused, the higher the political hurdle to using it will become.

Despite its drawbacks, challenge inspection remains a key verification tool because it can potentially expose clandestine chemical weapons development and production and thereby help to deter such violations. If challenge inspections are to serve as a credible deterrent, however, there must be a real possibility that one can be launched at any time, including the use of sampling and analysis to check for unscheduled chemicals.[26] To make challenge inspections more palatable, CWC member states should use them initially to resolve ambiguities, such as whether a particular facility should have been declared. Employing challenge inspections for clarification purposes might be necessary if the relevant information is not provided voluntarily. To prepare for future inspection requests and fine-tune its capabilities, the OPCW inspectorate should conduct more trial challenge inspections in various parts of the world, and member states should offer suitable military and industry facilities as targets for these exercises. For example, Germany hosted a mock challenge inspection in March 2006.[27]

Monitoring Role of National Authorities

The final element of the CWC safety net is the role in verification played by the states-parties themselves. Because the OPCW Technical Secretariat cannot monitor compliance with all of the obligations that the member states assume under the CWC, the treaty creates a division of labor between the verification activities of the OPCW Technical Secretariat at the international level and those of the states-parties at the national level.[28] According to Article VI, paragraph 2, the primary responsibility for monitoring compliance with the general purpose criterion rests with the member governments: “Each State Party shall adopt the necessary measures to ensure that toxic chemicals and their precursors are only developed, produced, otherwise acquired, retained, transferred, or used within its territory or in any other place under its jurisdiction or control for purposes not prohibited under this Convention.”

Article VII of the CWC also obligates member states to take “the necessary measures” to implement the treaty by adopting domestic implementing legislation that criminalizes the acquisition and use of chemical weapons by its citizens and restricts trade in related chemicals. This requirement has since been reinforced by UN Security Council Resolution 1540, which requires all UN members to adopt “appropriate” and “effective” national legislation to prevent the proliferation of nuclear, chemical, and biological weapons and related materials, especially for terrorist purposes. Article VII of the CWC also requires each member state to establish a “national authority” to oversee the domestic implementation of the treaty and serve as “the national focal point for effective liaison” with the OPCW and other states-parties. If implemented effectively, these measures should impede efforts by proliferators and terrorists to acquire a chemical warfare capability.

Surveys conducted by the OPCW Technical Secretariat suggest, however, that many member states have not yet adopted suitable domestic implementing legislation for the CWC.[29] In addition, an April 2006 report by the 1540 Committee to the UN Security Council stated that a total of only 69 states had enacted some prohibitions related to chemical weapons in their national legal framework.[30] To address the lack of implementing legislation and national authorities in many CWC member states, the first review conference in 2003 agreed to establish an action plan on national implementation. This effort should be expanded further to ensure that states-parties incorporate the general purpose criterion and the schedules of chemicals into their subsidiary regulations and empower their national authorities to collect all of the data needed to monitor domestic implementation effectively.


Nearly 10 years after its entry into force, the CWC has demonstrated its value as a disarmament vehicle and a nonproliferation tool for preventing the acquisition and use of chemical weapons by states and nonstate actors. Nevertheless, some major gaps in the verification regime threaten to undercut the treaty’s ability to achieve its potential. Not only is the planned safety net full of holes, but little is known about how the national authorities are discharging their verification obligations.

Another serious gap in the CWC is that it does not provide for the international monitoring of compliance with a number of important treaty obligations. These include the prohibition on providing technical or financial assistance to a chemical weapons program, the ban on exports to nonparties of Schedule 1 and 2 chemicals, and the requirement to obtain an end-use certificate for exports to nonparties of Schedule 3 chemicals. In the absence of formal verification tools, some states have developed ad hoc measures outside the CWC framework, such as the Proliferation Security Initiative. In principle, however, the treaty does not preclude the OPCW from developing additional monitoring procedures to cover these treaty obligations.[31]

More generally, the CWC will lack credibility as long as member countries have the leeway to cheat on their basic obligations with little risk of being detected and held accountable. To close the current gaps in the verification regime at the international and national levels, it is essential to reaffirm the central importance of the general purpose criterion, increase the number of OCPF inspections, expand the use of sampling and analysis during routine industry inspections, and start employing the challenge-inspection mechanism for clarification purposes, while taking additional steps to protect trade secrets and national security information unrelated to compliance. The 10th anniversary of the CWC in April 2007 provides a good opportunity to launch a serious discussion of these issues, including the drafting of an action plan to reverse the erosion of the verification regime. Ideally, this plan should be completed in time for consideration by the second review conference of the CWC, which will convene in The Hague in April 2008.

Technological Advances Present Challenge to CWC Verification

Rapid advances in chemical science and technology pose major new challenges for Chemical Weapons Convention verification. Today, the chemical and pharmaceutical industries make extensive use of combinatorial chemistry and high-throughput screening to synthesize thousands of novel compounds and screen them for desired physiological effects. Other powerful techniques such as genomics, proteomics, and systems biology are also being applied to identify natural body chemicals with useful medicinal properties, vastly expanding the range of compounds being detected and screened for their effects on living systems. Most of the chemicals identified during the drug discovery process have no commercial value and are rejected, but some highly toxic compounds might be secretly adapted for military purposes. Indeed, over the past 80 years, a number of compounds originally developed in industrial laboratories as pesticides or medicinal drugs have subsequently been converted into chemical warfare agents, including tabun, sarin, VX, and BZ.

Technological developments have also made it easier to conceal the manufacture of novel chemical warfare agents in the guise of legitimate industrial production. For example, some of the novichok nerve agents lack the carbon-phosphorus bond that is the hallmark of classical nerve agents such as sarin and soman, making the newer agents more difficult to identify. Several chemical warfare agents also come in binary formulations, in which two final precursor chemicals are mixed together inside a munition en route to the target and react to produce the lethal agent, which is then dispersed on impact. Because the binary components are relatively nontoxic, they can be manufactured in existing chemical plants for ostensibly legitimate purposes.

Paralleling these scientific and technological developments have been some dramatic changes in the structure of the international chemical industry. The production of synthetic chemicals by means of biologically mediated processes is increasingly blurring the line between the chemical and biotechnology industries. In addition, the advent of multipurpose manufacturing equipment has enabled chemical plants to switch rapidly from the production of one compound to another in response to shifts in market demand. Finally, hundreds of small “microreactors” could be operated in parallel to synthesize large volumes of chemicals in a small space, minimizing the traditional signatures associated with chemical warfare agent production. Microreactors also offer higher synthetic yields with fewer emissions of telltale by-products and may permit the use of unusual reaction pathways that are not feasible with conventional reactors.

All of these changes have made it possible for countries to acquire the capacity to manufacture large amounts of chemical warfare agents on short notice without having to stockpile them for long periods. Such a breakout capability is much more difficult to detect and monitor than a standing chemical weapons stockpile. The Organization for the Prohibition of Chemical Weapons will therefore have to adapt to these diverse technological developments by improving its verification strategies, a task that is easier said than done.

Jonathan B. Tucker is a Fulbright senior scholar at the German Institute for International and Security Affairs in Berlin, on leave from the Monterey Institute’s Center for Nonproliferation Studies. He is author of War of Nerves: Chemical Warfare From World War I to al-Qaeda, which Anchor Books will publish in paperback in February.


1. The Chemical Weapons Convention (CWC) verification regime is set out in Articles III through VI and in the 209-page Verification Annex.

2. Nonparties to the CWC that are suspected of possessing chemical weapons stockpiles include Egypt, Israel, North Korea, and Syria.

3. The 12 CWC states-parties that have declared former chemical weapons production facilities are Bosnia and Herzegovina, China, France, India, Iran, Japan, Libya, the Russian Federation, Serbia, South Korea, the United Kingdom, and the United States. Of 65 declared former production facilities, 57 have been certified as destroyed or converted to civilian use.

4. Verification Research, Training and Information Centre (VERTIC), Getting Verification Right: Proposals for Enhancing Implementation of the Chemical Weapons Convention ( London: VERTIC, 2002), p. 4.

5. The Soviet development of the novichok nerve agents was revealed in 1991 by a Russian chemist, Vil Mirzayanov, who was subsequently arrested by the Russian Federal Security Service and put on trial in Moscow for disclosing state secrets. The charges against him were later dropped for lack of evidence.

6. Whether the CWC permits the development and use for domestic law enforcement purposes of incapacitating agents with long-lasting effects, in addition to riot-control agents with transient effects such as CS tear gas, is a matter of intense debate, particularly in the context of the international war on terrorism. In October 2002, Russian special forces used an incapacitating gas containing a powerful opiate anesthetic during a counterterrorism operation to rescue hostages seized by Chechen militants at the Dubrovka Theater in Moscow. More than 120 hostages died from the effects of the gas, making clear that it was not truly nonlethal. Arms control experts noted the pharmacological differences between incapacitants and riot-control agents and questioned the legality of the Moscow theater operation under the law enforcement exemption of the CWC. Others argued that the paramilitary operation was an extension of the war in Chechnya and thus violated the treaty’s total ban on the use of toxic chemicals in combat.

7. Organization for the Prohibition of Chemical Weapons (OPCW) Technical Secretariat, “Note by the Director-General: Report of the Scientific Advisory Board on Developments in Science and Technology,” RC-1/DG.2, April 23, 2003, p. 11, para. 3.3.

8. Kingdom of Sweden, “Technological Development and Industry Inspections,” RC-1/NAT.28, May 8, 2003, p. 2.

9. U.S. General Accounting Office, Delays in Implementing the Chemical Weapons Convention Raise Concerns About Proliferation, GAO-04-361, March 2004, pp. 17-18.

10. Jiri Matousek, “Chemical Weapons Convention: Status and Actual Problems of Implementation,” 25th Workshop of the Pugwash Study Group on the Implementation of the CWC and BTWC, Geneva, November 18-19, 2006.

11. Ralf Trapp, “The Chemical Weapons Convention—Multilateral Instrument With a Future,” in The Chemical Weapons Convention: Implementation, Challenges and Opportunities, eds. Ramesh Thakur and Ere Haru ( New York: UN University Press, 2006), p. 29.

12. OPCW Technical Secretariat, “Note by the Director-General,” p. 17, para. 4.4(a).

13. OPCW Executive Council, “Report of the OPCW for 2005,” C-11/4, Dec. 6, 2006, p. 7.

14. Alexander Kelle, “The CWC After Its First Review Conference: Is the Glass Half Full or Half Empty?” Disarmament Diplomacy, No. 71 (June-July 2003) (citing Ambassador and Permanent Representative of Pakistan to the OPCW Mustafa Kamal Kazi, “Statement to the First Special Session of the Conference of States Parties to Review the Operation of the Chemical Weapons Convention,” April 30, 2003).

15. OPCW Technical Secretariat, “Note by the Technical Secretariat: Support by Inspected States Parties for Sampling and Analysis Under Article VI of the Chemical Weapons Convention,” S/548/2006, February 10, 2006.

16. Ron G. Manley, “Verification Under the Chemical Weapons Convention: A Reflective Review,” Pure and Applied Chemistry, Vol. 74, No. 12 (December 2002), p. 2239.

17. Daniel Feakes, “Evaluating the CWC Verification System,” Disarmament Forum, No. 4 (2002), p. 19.

18. Bureau of Industry and Security, U.S. Department of Commerce, “Chemical Weapons Convention: Sampling and Analysis,” Chemical Weapons Convention Bulletin (2006).

19. AMDIS stands for Automated Mass Spectral Deconvolution and Identification System.

20. OPCW Technical Secretariat, “Note by the Director-General,” p. 21, para. 5.10.

21. OPCW Technical Secretariat, “Background Paper on the Conduct of Inspections Under the Chemical Weapons Convention and Related Issues,” RC-1/S/1, April 17, 2003, para. 10.11.

22. Similarly, the International Atomic Energy Agency uses outside reference laboratories to conduct blind checks to help determine the source of a particular sample of uranium.

23. Condition No. 18 of the Executive Resolution on Ratification of the CWC by the U.S. Senate, dated April 24, 1997, states that “[p]rior to the deposit of the United States instrument of ratification, the President shall certify to the Senate that no sample collected in the United States pursuant to the Convention will be transferred for analysis to any laboratory outside the territory of the United States.”

24. For the U.S. chemical weapons allegations against Iran and Sudan, see Stephen G. Rademaker, “National Statement to the First Review Conference of the Chemical Weapons Convention,” April 28, 2003. See also Bureau of Verification and Compliance, U.S. Department of State, Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments, August 30, 2005.

25. OPCW, First Conference of the States Parties, Decision No. 45, “Illustrative List of Objective Indicators to Facilitate the Executive Council in Addressing Any Concern, in Accordance with Paragraph 22 of Article IX, Whether the Right to Request a Challenge Inspection Has Been Abused,” C-I/DEC.45, May 16, 1997.

26. Blinded software was originally developed as a form of managed access that may be requested by the inspected state-party during a challenge inspection. Nevertheless, the use of managed access is conditioned by the requirement that the inspection team must be able to carry out its mandate. For example, if the challenge inspection request is based on suspicion that novel chemical weapons are being developed, produced, or stockpiled, the use of blinded software would not be appropriate, and the inspection team could insist on conducting analyses in open mode. If the request is denied, the inspection team would report that the inspected state-party had prevented it from fully implementing its inspection mandate, a finding that would influence the subsequent evaluation of the inspection outcome by the OPCW Executive Council. Ralf Trapp, personal communication with author, November 28, 2006.

27. OPCW, “Germany Hosts Challenge Inspection Exercise,” April 6, 2006 (press release).

28. Julian Perry Robinson, personal communication with author, November 24, 2006.

29. Lisa Tabassi and Scott Spence, “Improving CWC Implementation: The OPCW Action Plan,” Verification Yearbook 2004 ( London: VERTIC, 2004), pp. 45-64.

30. “Letter Dated 25 April 2006 From the Chairman of the Security Council Committee Established Pursuant to Resolution 1540 (2004) Addressed to the President of the Security Council,” S/2006/257, April 25, 2006, p. 13.

31. Sergey Batsanov, “Approaching the 10th Anniversary of the Chemical Weapons Convention: A Plan for Future Progress,” The Nonproliferation Review, Vol. 13, No. 2 (July 2006), p. 349.