On November 27, 2019, the 24th Conference of State Parties to the Chemical Weapons Convention (CWC), convened in the Hague, approved two proposals for the amendment of the treaty’s Annex on Chemicals, adding novichok and carbamate nerve agents to Schedule 1.

The addition of these nerve agents to the CWC Schedules has the effect of subjecting them to the CWC verification regime and declaration requirements, which for Schedule 1 chemicals are particularly stringent.

This is the first time that the CWC Schedules – lists of toxic chemicals and precursors for their synthesis intended to support the Convention’s implementation and its verification regime – are updated since the CWC entered into force in 1997.

The two proposals were put forth in the aftermath of the March 2018 attempted assassination of Sergei Skripal and his daughter in Salisbury, UK, with a novichok nerve agent.

One proposal, composed of two elements, was jointly submitted by the United States, Canada and the Netherlands. The second proposal, composed of five elements, was submitted by the Russian Federation.

In a paper published in The Nonproliferation Review, Gregory Koblentz and I recommended the adoption of the joint proposal, which is similar to the first two elements of the Russian proposal but has a wider scope, as well as the adoption of the third and fourth elements of the Russian proposal, which comprise chemicals not covered by the joint proposal.

We also recommended that Russia dropped the fifth element of its proposal so that consensus could be reached, as the Technical Secretariat of the Organization for the Prohibition of Chemical Weapons deemed the chemicals contained in it not suitable for addition to CWC Schedule 1.

Following negotiations between the joint proponents and the Russian Federation, Russia did modify its proposal, replacing the first two elements with the version contained in the joint proposal, and dropping the fifth element. This cleared the road for the acceptance of both proposals by consensus by the Conference of State Parties.

The chemicals added to CWC Schedule 1 include:

1) Two large families of novichok organophosphorus nerve agents, which comprise the agent used in Salisbury – these are the two elements of the joint proposal, subsequently incorporated into the Russian proposal;

2) An additional novichok organophosphorus nerve agent not covered by the joint proposal – this is the third element of the Russian proposal;

3) A family of carbamate researched as chemical warfare agents in the United States during the Cold War – this is the fourth element of the Russian proposal.

Novichok agents are organophosphorus nerve agents developed in the Soviet Union during the Cold War. The structures of the novichok agents that were just added to CWC Schedule 1 were publicly disclosed for the first time by Vil Mirzayanov, an analytical chemist involved in the Soviet chemical weapons program.

The carbamates that were just added to CWC Schedule 1 are not chemically related to novichoks and are not organophosphorus nerve agents. However, the biochemical bases of their toxicity are similar to those of organophosphorus nerve agents.

It is worth clarifying that even prior to the addition of these nerve agents to the CWC Schedules, their use as chemical weapons was prohibited by the CWC. In fact, according to the CWC’s provisions, any weapon that exploits the toxicity of chemicals to intentionally kill of harm humans or animals is considered a chemical weapon.

The amendment will enter into force 180 days after the OPCW Director General notifies all State Parties and the Unites Nations Secretary General of the decision reached by the Conference of State Parties.

To further strengthen the Convention, given that the third element of the Russian proposal contains exclusively a single chemical, it is advisable to further amend the CWC schedules to cover the whole family of chemicals to which this specific chemical belongs. Moreover, as Gregory Koblentz and I recommended in our The Nonproliferation Review paper, it is advisable to add to the CWC schedules another family of novichoks described by Mirzayanov that still remains uncovered by the CWC schedules.

Lastly, as Gregory Koblentz and I recommended in our The Nonproliferation Review Paper, it will be important to conduct a thorough assessment of key precursors for the synthesis of novichok agents and assess the need to amend the CWC schedules accordingly.

A table with the text of the additions to CWC Schedule 1 approved by the CWC Conference of State Parties, annotated with chemical structures, is reported below.