Action 14 - NPT Monitor

China

What has the NWS done so far (prior to the current Review Cycle 2022–2026)?

China has undertaken construction and certification of CTBTO International Monitoring System stations and the Beijing radionuclide laboratory. China has expanded its contribution to the International Monitoring System:

As of 2014, China has undertaken the construction work of 11 monitoring stations and one radionuclide laboratory of the International Monitoring System, of which 6 seismic stations, 3 radionuclide stations, the Beijing radionuclide laboratory and the National Data Center in Beijing have been completed.
As of 2019, radionuclide stations in Beijing, Guangzhou, Lanzhou, and seismic stations in Hailar, Lanzhou have been certified and began real-time data transmission; China has accelerated the certification of remaining infrasound stations (e.g., Kunming).

China has developed advanced verification technologies, including mobile Ar-37 measurement system (MARDS), and radioxenon sampling and analysis systems (XESPM). Contributed equipment and expertise to Integrated Field Exercise 2014 (IFE14).

China has provided support for developing countries in CTBT capacity-building by hosting regional and international CTBTO training workshops.

China has provided critical monitoring data during real-world nuclear events (e.g, DPRK tests on 6 January and 9 September 2016 and 3 September 2017, and the Fukushima incident).

What is the NWS doing on this action in the current Review Cycle 2022–2026?

China has actively supported the building of the verification regime of the CTBT, and a number of monitoring stations in China havebeen certified. China has undertaken the construction of 11 monitoring stations and one radionuclide laboratory. All of the facilities have been completed except for the infrasound station in Beijing (IS15), as site selection is still under way. At present, the Lanzhou radionuclide station (RN21), the Beijing radionuclide station (RN20), the Guangzhou radionuclide station (RN22), the Hailar primary seismic station (PS12) and the Lanzhou primary seismic station (PS13) have been certified. In August 2025, the Kunming infrasound station (IS16) was certified. In October 2025, certification of the Xi’an and Shanghai auxiliary seismic stations was initiated.

China has continued CTBTO technical cooperation, including capacity-building and verification-related scientific exchanges.

Sources

Implementation of the Treaty on the Non-Proliferation of Nuclear Weapons–Report submitted by the People’s Republic of China, NPT/CONF.2015/32, 17 April 2015

Implementation of the Treaty on the Non-Proliferation of Nuclear Weapons in the People’s Republic of China, NPT/CONF.2020/41, 28 January 2022

White Paper: China’s Arms Control, Disarmament, and Nonproliferation in the New Era, State Council Information Office, November 27, 2025

Remarks by Ambassador Geng Shuang, September 22, 2023

White Paper: China’s Arms Control, Disarmament, and Nonproliferation in the New Era, November 27, 2025

Implementation of the Treaty on the Non-Proliferation of Nuclear Weapons in the People’s Republic of China, NPT/CONF.2026/33, 17 April 2026

First station certified in China, 16 December 2016

France

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What has the NWS done so far (prior to the current Review Cycle 2022–2026)?

France has been tasked with the deployment and operation of 16 stations of the International Monitoring System (IMS) on its territory and provides technical assistance for the operation and maintenance of eight stations abroad. It also operates a radionuclide measurement laboratory certified by the CTBTO. The last station under French responsibility, in Guadeloupe, was completed and became operational on 5 December 2019, allowing France to become the first NWS to have completed its contribution to the IMS.

What is the NWS doing on this action in the current Review Cycle 2022–2026?

France has published working papers supporting the International Monitoring System (IMS) and organised a side-event during the 2025 NPT Preparatory Committee, in New York, entitled “Supporting the CTBTO International Monitoring System: a unique tool for the Treaty verification regime and the scientific and civil applications”

Sources

Working Paper. Sustaining the International Monitoring System of the Comprehensive Nuclear-Test -Ban -Treaty Organization: a critical step for the credibility of compliance with the nuclear test moratorium and the services the System provides to the whole international community. NPT/CONF.2026/PC.III/WP.38 (New York), 9 May 2025. https://docs.un.org/en/NPT/CONF.2026/PC.III/WP.38

CTBTO. Activities Undertaken by Signatory and Ratifying States Under Measure (L) of the Final Declaration of the 2025 Conference on Facilitating the Entry into Force of the Treaty in the Period June 2023 – May 2025. CTBT-Art.XIV/2025/4. May 2025. https://www.ctbto.org/sites/default/files/2025-09/CTBT-Art.XIV-2025-4.pdf

Working Paper. France and the Comprehensive Nuclear-Test-Ban Treaty: an exemplary nuclear-weapon State supporting a unique tool in the disarmament and non-proliferation architecture. NPT/CONF.2026/PC.III/WP.10. 4 March 2025. https://docs.un.org/en/NPT/CONF.2026/PC.III/WP.10

Russia

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What has the NWS done so far (prior to the current Review Cycle 2022–2026)?

Russia has consistently expressed support for the establishment of a mechanism for the verification of compliance with the CTBT. Russia has further supported the establishment of the verification system in following ways:

Russia has worked on constructing, certifying and maintaining CTBT International Monitoring System (IMS) facilities in its territory
Russia organized annual training courses at the National Data Centre for the staff of IMS stations and worked on developing technical models for IMS stations, including a high-performance noble gas detection system.
Russia provided technical support and expertise towards the development of the CTBT’s on-site inspection protocols and detection capabilities

What is the NWS doing on this action in the current Review Cycle 2022–2026?

In November 2023 Russia has revoked its ratification of the CTBT. Russia continued to be a signatory to the CTBT and to participate in the work of the CTBTO.

Russia has reaffirmed its commitment to the goals and objectives of the CTBT, as well as support for the establishment of the Treaty’s verification regime.

In 2023, Russia completed the construction of its national segment of the International Monitoring System, which is the second largest in the world and consists of 32 facilities

Russia continued to engage in the work of the CTBTO involving the discussion of relevant issues, including the on-site inspection regime.

Russia continued to organize annual training courses at the National Data Centre for the staff of IMS stations and work on developing technical models for IMS stations, including a high-performance noble gas detection system.

Sources

National report of the Russian Federation, 2020 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (New York), 19 March 2021.

https://docs.un.org/en/NPT/CONF.2020/17/Rev.1

United Nations. Russian Federation: Withdrawal of the instrument of ratification, 2 November 2023

https://treaties.un.org/doc/Publication/CN/2023/CN.463.2023-Eng.pdf

National report of the Russian Federation, 2026 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (New York), 2 March 2026.

https://docs.un.org/en/NPT/CONF.2026/14

United Kingdom

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What has the NWS done so far (prior to the current Review Cycle 2022–2026)?

The UK signed the CTBT in 1996 and completed ratification in 1998, being one of the first two nuclear-weapon states to do so alongside France. The UK has not conducted any nuclear weapon test explosion or any other nuclear explosion since 1991.

What is the NWS doing on this action in the current Review Cycle 2022–2026?

The United Kingdom states that it “provides extensive technical support to the three pillars of the CTBTO’s verification framework. The UK is actively engaged in relevant work streams aimed at improving the capabilities of the International Monitoring System and the International Data Centre, alongside development of the On-Site Inspection methodology. Over 90% of UK-based International Monitoring System stations are complete and operational.”

Sources

Foreign, Commonwealth and Development Office (2026). National report of the United Kingdom of Great Britain and Northern Ireland pursuant to actions 5, 20 and 21 of the action plan of the 2010 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons for the eleventh Review Conference of the Parties to the Treaty. <https://assets.publishing.service.gov.uk/media/69df600a53469bbcdf408e8b/UK-National-Report-11th-Treaty-on-the-Non-Proliferation-of-Nuclear-Weapons-NPT-Review-Conference.pdf>

United States

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What has the NWS done so far (prior to the current Review Cycle 2022–2026)?

The United States made the largest annual financial contribution to the CTBTO Preparatory Commission between the 2010 and 2020 NPT Review Conferences, paying more than 22 percent of the Commission’s annual budget and voluntarily funding elements of the International Monitoring System.

In particular, the United States contributed more than $63 million to CTBTO projects, including the reengineering of the International Data Centre’s analysis software, and the repair and rebuilding of IMS stations HA08 (Diego Garcia) and HA04 (Crozet Island). It also continued to provide data from the IMS stations under its purview. In addition, the United States convened meetings of technical experts and contributed equipment, expertise, and research towards developing the on-site inspection element of the CTBT’s verification regime, including as part of the largest ever on-site expective exercise in Jordan in December 2014.

What is the NWS doing on this action in the current Review Cycle 2022–2026?

During the review period, the United States has continued to provide substantial contributions to the development and maintenance of the CTBTO’s verification regime. In particular, the United States has been one of the leaders in the effort to modernize and re-engineer the International Data Centre, which collects and analyses data to share with the Member States. In addition, the United States has made contributions in kind to the International Noble Gas Experiment, which is designed to optimize the capability of the International Monitoring System in detecting signals from nuclear explosions against the global background of natural and human-made radionuclides.

Sources

United States of America. “Actions 5, 20 and 21 of the Action Plan of the 2010 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons: Report Submitted by the United States of America.” NPT/CONF.2015/38. 2015 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, United Nations, New York, April 27–May 22, 2015. https://docs.un.org/en/NPT/CONF.2015/38.

Comprehensive Nuclear-Test-Ban Treaty Organization. “Crozet Islands: Installing Our Last Hydroacoustic Station.” April 18, 2016. https://www.ctbto.org/news-and-events/news/crozet-islands-installing-our-last-hydroacoustic-station.

United States of America. “Actions 5, 20 and 21 of the Action Plan of the 2010 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons: Report Submitted by the United States of America.” NPT/CONF.2020/47. Tenth Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, United Nations, New York, August 1–26, 2022. https://docs.un.org/en/NPT/CONF.2020/47.

Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization. Background Document Prepared for the Conference on Facilitating the Entry into Force of the CTBT (New York, 2025). CTBT-Art.XIV/2025/3. Vienna: CTBTO, August 19, 2025. https://www.ctbto.org/sites/default/files/2025-09/CTBT-Art.XIV-2025-3.pdf.