Chemical Weapons Convention (CWC)

The Chemical Weapons Convention (CWC) is a binding international disarmament and non-proliferation treaty with the objective to outlaw chemical weapons. A distinctive feature of the CWC is its robust verification regime, which helps to achieve the Convention's objectives.

What are chemical weapons?

Chemical weapons are toxic chemicals and their precursors, as well as munitions and devices for their release. Toxic chemicals are those that can cause death, temporary incapacitation or permanent damage to humans and animals. Precursors are chemical reaction components that are involved in the production of a toxic chemical at any stage. Chemical weapons are considered weapons of mass destruction and are outlawed under international law by the CWC.


The Convention prohibits the development, production, stockpiling, transfer and use of chemical weapons and requires the destruction of any stockpiles by its Member States.


Following the devastating use of chemical weapons in the First World War, the States Parties to the Geneva Protocol agreed in 1925, and still in force today, to ban the use of asphyxiating, poisonous or similar gases and bacteriological agents in warfare. With the entry into force of the Chemical Weapons Convention in 1997, this prohibition was explicitly extended to the development, production, stockpiling and transfer of chemical weapons.

The CWC is binding under international law, and the 193 Member States are required to declare CWC-relevant activities and to permit inspections on their territory. Compliance with the Convention is monitored by the Organization for the Prohibition of Chemical Weapons (OPCW), based in The Hague.

In principle, any toxic chemical or precursor is defined as a chemical weapon unless it is used for activities explicitly permitted by the CWC (General Purpose Criterion). Thus, the Convention does not restrict the right of a State Party to produce and use chemicals for peaceful purposes. In addition, there are chemicals that pose a particular risk and are therefore subject to the CWC's verification regime. The controlled chemicals are divided into three lists, depending on their relevance to chemical weapons. In addition to these listed chemicals, certain organic chemicals and compounds are also subject to controls under the CWC. The Australia Group, whose 42 participating States are also parties to the CWC, supports the implementation of the CWC non-proliferation obligation through internationally harmonized export controls.

In addition to industry verification, the OPCW assists States in destroying chemical weapons. To date, 98% of officially declared chemical weapons stockpiles have been destroyed. However, some OPCW Member States that have not yet completely destroyed their stockpiles. In addition, the OPCW supports the development of national chemical weapons protection programmes and the capacity to respond to chemical weapons use.

The OPCW established the Investigation and Identification Team (IIT) in 2018. This body evolved from the Joint Investigative Mechanism (JIM), which was established in cooperation with the UN to investigate the use of chemical weapons in Syria and whose mandate expired in 2017. In the case of suspected chemical weapons use in Syria, the IIT conducts an investigation and collects information that helps identify the source of the chemical weapon. The results of the investigation are made publically available in a report. The OPCW also supported the analysis of toxic chemicals in the case of the Salisbury attacks in 2018 as well as on Alexei Nawalny in 2020. In 2013, the OPCW was awarded a Nobel Peace Prize for ‘its extensive efforts to eliminate chemical weapons.’

Consquences for Switzerland

Switzerland participates in the annual Conference of the States Parties and, as required by the CWC, has designated a National Authority for its implementation. Its role is to assist in the monitoring of those activities that are not prohibited by the CWC.

The industry carrying out such activities is subject to certain declaration and inspection obligations. The export (as well as under specific conditions the import and production) of listed chemicals requires a license from SECO and the export of certain chemicals to non-Member States is prohibited.

Inspections are carried out by an OPCW multinational inspection team, which routinely monitors compliance by visiting companies in all State Parties that declare CWC-relevant activities. These inspections, which are announced at short notice, may include plant site inspections, review of the company’s records, and analysis of samples. In Switzerland, a team from the federal administration under the direction of SECO accompanies the OPCW inspection team.

CWC Member States

Karte CWÜ_neu

CWC Key Info

  • Entry into force: 1997
  • Entry into force in Switzerland: 1997
  • Members: 193

Last modification 09.09.2021

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