Preventing the Re-Emergence of Chemical Weapons

“To exclude completely the possibility of the use of chemical weapons”

The Chemical Weapons Convention’s aim is “to exclude completely the possibility of the use of chemical weapons”. It does so by ensuring that all existing stockpiles of chemical weapons are destroyed, and by putting in place a framework – made up of a set of binding obligations on States Parties and a verification regime run by the Technical Secretariat – to ensure that chemical weapons do not re-emerge. 

Chemical weapons may re-emerge in a number of ways: through state-sponsored programmes, through the actions of terrorist or other criminal groups, or through lone individuals. Chemical weapons may be produced by repurposing existing chemical facilities or they may be made on a smaller scale in purpose-built laboratories or even domestic settings. The OPCW works in a variety of ways to prevent these scenarios from happening.


Toxic chemicals are used around the world for many legitimate and peaceful applications, but they may also be used for purposes that are prohibited by the Chemical Weapons Convention.  Because of this, States Parties to the Chemical Weapons Convention must ensure that all toxic chemicals, and their precursors, are only used for purposes that are not prohibited by the Convention. This is a very broad obligation, which may involve a number of actions at the national level relating to matters such as chemical security, criminalisation of prohibited conduct, and the creation of a National Authority for Convention implementation.

As part of this commitment, States Parties to the Convention have obligations relating to certain toxic chemicals that are listed in the Convention and that could be used for weapons purposes. These obligations involve the collection of information and the submission of declarations regarding these chemicals, which are of varying commercial significance. 

Based on the information provided in States’ declarations, OPCW inspectors visit the facilities where these chemicals are produced, processed, or consumed to ensure that the declarations are complete and accurate. These routine inspections are cooperative events—the inspection teams are concerned with verifying the contents of declarations and do not adopt an investigative approach.


Controlling International Transfers of Chemicals

States Parties to the Convention also have obligations when they export or import scheduled chemicals. There are two basic elements to the Convention’s regime concerning international transfers of chemicals: monitoring transfers between States Parties, and restrictions on trade with non-States Parties. 

In brief, Schedule 1 and 2 chemicals may only be transferred between States Parties to the Convention. Schedule 3 chemicals may only be transferred to non-States Parties if the recipient provides an end-use certificate and pledges not to transfer them onward. All transfers of scheduled chemicals must be declared to the OPCW Technical Secretariat.

Challenge Inspections

Challenge inspections are designed to clarify and resolve any questions concerning possible non-compliance by a State Party with the Chemical Weapons Convention and are one of its most innovative features. Under Article IX of the Convention, any State Party can request the Secretariat to conduct an on-site challenge inspection anywhere in the territory (or under the jurisdiction or control) of any other State Party. States Parties may not refuse a challenge inspection, regardless of the nature of the location at which it is to take place. Article IX encourages, but does not oblige, States Parties to try to clarify and resolve non-compliance concerns through consultations before requesting a challenge inspection. Challenge inspections are characterised by the ‘any time, any place’ concept: they are to be launched at very short notice and can be directed at declared or undeclared facilities and locations.

Dealing with the Threat of Terrorism

The threat of terrorists using chemicals as weapons is a significant global challenge. OPCW Member States have long recognised the threat posed to the Chemical Weapons Convention by non-State actors, and have underlined that the full and effective implementation of all provisions of the Chemical Weapons Convention is in itself a contribution to global counter-terrorism efforts. While the Chemical Weapons Convention was not designed specifically to deal with terrorism, it contains a number of provisions that can help countries to control access to toxic chemicals and related materials, and to respond effectively should the worst occur.


Key to preventing chemical terrorism is ensuring that terrorists cannot easily access the chemicals they seek. The Chemical Weapons Convention requires its States Parties to “adopt the necessary measures” to ensure that toxic chemicals and their precursors are only used for non-prohibited purposes. The implementation of this obligation involves ensuring compliance with the requirements of the Convention’s verification regime in relation to scheduled chemicals, but it also involves putting in place controls, where considered necessary, on scheduled or non-scheduled chemicals that are susceptible to being used as weapons or in the manufacture of chemical weapons. An example of a non-scheduled chemical of security concern is chlorine, which is in very wide industrial use around the world but has also been used recently as a chemical weapon.

Possible examples of such ‘necessary measures’ include policies to ensure the security and to limit the risk of diversion of vulnerable chemicals (such as chemicals or precursor chemicals that may likely be used by non-State actors), including declaration and reporting requirements, codes of practice, export controls, and so forth.

The OPCW assists its Member States in this task by serving as a platform for the exchange of information about best practices and by providing capacity building.


The Convention facilitates the exchange among States Parties of information and equipment which can help to protect populations against the effects of a chemical weapons attack. It also mandates the Technical Secretariat to provide assistance to States Parties that request it.

Legal Accountability

An important part of dealing with the threat of chemical terrorism is ensuring that those who plan or carry out such attacks are brought to justice. The Chemical Weapons Convention requires each State Party to adopt laws that criminalise all conduct that is prohibited for States by the Convention (Article VII). This means that individuals and corporations can be prosecuted in national courts if they develop, produce, otherwise acquire, retain, transfer, or use chemical weapons. The Convention also requires States Parties to provide to each other the necessary legal assistance to ensure legal accountability.

Awareness through Education and Outreach

One of the most important ways the OPCW works to prevent the re-emergence of chemical weapons is by increasing knowledge and awareness about chemical weapons, about the work of the OPCW and the goals of the CWC, and about the importance of responsible scientific practice.

The Hague Ethical Guidelines

Ensuring an Ethos of Science for Peace

To promote a culture of responsible conduct in the chemical sciences and to guard against the misuse of chemistry, a group of chemical practitioners from around the world have formulated a set of ethical guidelines informed by the Chemical Weapons Convention – The Hague Ethical Guidelines.

The Hague Ethical Guidelines are intended to serve as elements for ethical codes and discussion points for ethical issues related to the practice of chemistry under the Convention. The OPCW encourages all stakeholders to refer to and promote the guidelines when debating the vital dimension of ethics in relation to chemical disarmament and non-proliferation and the broader issue of responsible scientific conduct.


The Key Elements

Achievements in the field of chemistry should be used to benefit humankind and protect the environment.



Chemistry practitioners have a special responsibility for promoting and achieving the UN Sustainable Development Goals of meeting the needs of the present without compromising the ability of future generations to meet their own needs.


Education and Outreach

Formal and informal educational providers, enterprise, industry and civil society should cooperate to equip anybody working in chemistry and others with the necessary knowledge and tools to take responsibility for the benefit of humankind, the protection of the environment and to ensure relevant and meaningful engagement with the general public.

Speech Bubbles

Awareness and Engagement

Teachers, chemistry practitioners, and policymakers should be aware of the multiple uses of chemicals, specifically their use as chemical weapons or their precursors. They should promote the peaceful applications of chemicals and work to prevent any misuse of chemicals, scientific knowledge, tools and technologies, and any harmful or unethical developments in research and innovation. They should disseminate relevant information about national and international laws, regulations, policies and practices.



To adequately respond to societal challenges, education, research and innovation must respect fundamental rights and apply the highest ethical standards. Ethics should be perceived as a way of ensuring high quality results in science.


Safety and Security

Chemistry practitioners should promote the beneficial applications, uses, and development of science and technology while encouraging and maintaining a strong culture of safety, health, and security.



Chemistry practitioners have a responsibility to ensure that chemicals, equipment and facilities are protected against theft and diversion and are not used for illegal, harmful or destructive purposes. These persons should be aware of applicable laws and regulations governing the manufacture and use of chemicals, and they should report any misuse of chemicals, scientific knowledge, equipment and facilities to the relevant authorities.



Chemistry practitioners who supervise others have the additional responsibility to ensure that chemicals, equipment and facilities are not used by those persons for illegal, harmful or destructive purposes.


Exchange of Information

Chemistry practitioners should promote the exchange of scientific and technical information relating to the development and application of chemistry for peaceful purposes.