A) Signing and ratifying the CTBT

As of the end of 2023, 177 of the 187 signatories have deposited their instruments of ratification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). As mentioned below, Russia revoked its ratification of the treaty.

Among the 44 states listed in Annex 2 of the CTBT, ratification of which is a prerequisite for the treaty’s entry into force, six states (China, Egypt, Iran, Israel, Russia and the United States) have signed but not ratified, and three (India, North Korea and Pakistan) have not signed. Among the countries surveyed, Saudi Arabia and Syria as well have yet to sign the CTBT.

In his address to the Federal Assembly in February 2023, Russian President Putin announced a suspension on implementing the New START and stated, “If the US conducts [nuclear] tests, we will also conduct them,” implying a possible resumption of nuclear explosion tests.212 In October, President Putin highlighted that Russia had signed and ratified the CTBT, in contrast to the United States which has not ratified it. He also said that it was theoretically possible for the Russian parliament to revoke its ratification of the treaty.213 In response, Chairman of the State Duma Vyacheslav Volodin said on October 6, “The situation in the world has changed. Washington and Brussels have unleashed a war against our country. Today’s challenges require new solutions.” He also suggested swiftly contemplating the need to de-ratify the CTBT.214 In his social media, CTBT Special Envoy Mikhail Ulyanov stated, “[Russia’s de-ratification of the CTBT] aims to be on an equal footing with the US, which signed the treaty but did not ratify it. The revocation doesn’t mean the intention to resume nuclear tests.”215 The Russian Duma (on October 18) and the Federal Assembly (on October 25) unanimously passed the law to revoke its ratification. President Putin signed the law on November 2.

In the meantime, on September 22, the 13th Conference on Facilitating the Entry into Force of the CTBT was convened, which more than 80 countries attended. In the Final Declaration, participants reaffirmed their determination to take concrete and actionable steps towards early entry into force and universalization of the CTBT. They also agreed to conduct active outreach activities.216

Prior to this conference, on August 29, a meeting was held at the UN Headquarters to commemorate the International Day Against Nuclear Tests, which was established at the initiative of Kazakhstan. In addition, Japan hosted a regional meeting in Tokyo on July 6 to promote the entry into force of the CTBT, where various issues, such as universalization of the treaty and verification technologies were discussed.217

At the 2023 UNGA, a resolution, titled “Comprehensive Nuclear-Test-Ban Treaty,”218 in which member states emphasized the vital importance and urgency of signature and ratification, without delay and without conditions, to achieve the earliest entry into force of the CTBT, was adopted with 181 countries in favor, one against (North Korea) and four abstentions (India, Saudi Arabia, Syria and others).
Regarding outreach activities for promoting the treaty’s entry into force, a document, titled “Activities Undertaken by Signatory and Ratifying States Under Measure (K) of the Final Declaration of the 2015 Article XIV Conference in the Period June 2022-May 2023,”219 was distributed at the Article XIV Conference on Facilitating the Entry-Into-Force of the CTBT, and summarized activities conducted by ratifying and signatory states. It highlighted:

➢ Bilateral activities related to Annex 2 states (conducted by Australia, Japan, New Zealand, Russia, Switzerland, the United Kingdom, the United States and others);

➢ Bilateral activities related to non-Annex 2 states (conducted by Australia, Japan, New Zealand, Russia, the United Kingdom, the United States and others);

➢ Global-level activities (conducted by Australia, Japan, South Korea, Mexico, New Zealand, Russia, Switzerland, the United Kingdom, the United States and others); and

➢ Regional-level activities (conducted by Australia, Mexico, New Zealand, Russia, the United States and others).

 

B) Moratoria on nuclear test explosions pending CTBT’s entry into force

The five NWS plus India and Pakistan maintain a moratorium on nuclear test explosions. As noted above, Russia repeatedly stated that as long as the United States does not conduct nuclear explosion tests, it would not do so either. Israel, which has kept its nuclear policy opaque, has not disclosed the possibility of conducting nuclear tests.
North Korea, at the Plenary Meeting of the Central Committee of the Workers’ Party of Korea on April 20, 2018, decided to stop nuclear tests and test launches of longer-range ballistic missiles. However, Chairman Kim Jong Un stated in late December 2019 that “the DPRK has found no grounds to be unilaterally bound any longer by the commitment” to stop nuclear and longer-range ballistic missiles tests.220 In January 2022, Chairman Kim instructed relevant departments to reevaluate the moratorium on longer-range ballistic missiles launch tests and nuclear explosion tests, and to consider the issue on resuming them promptly.221 Since May 2022, there have been occasional reports suggesting that North Korea had completed preparations for a nuclear explosion test. However, as of the end of 2023, North Korea had not resumed nuclear explosion tests.

 

C) Cooperation with the CTBTO Preparatory Commission

Regarding the countries surveyed in this study, the status of their contribution payments to the CTBTO, as of December 31, 2023, is as follows.222

➢ Fully paid: Australia, Austria, Brazil, Canada, China, Egypt, France, Germany, Indonesia, Israel, Japan, Kazakhstan, Mexico, the Netherlands, New Zealand, Norway, Poland, Russia, Sweden, Switzerland, Turkey, the United Kingdom, and the United States

➢ Partially paid: South Korea and South Africa

➢ Voting right in the Preparatory Commission suspended because arrears are equal to or larger than its contributions due for the last two years: Iran

 

D) Contribution to the development of the CTBT verification systems

The establishment of the CTBT verification system has progressed steadily. The pace of establishing International Monitoring System (IMS) stations in Egypt and Iran—in addition to those in India, North Korea, Pakistan and Saudi Arabia, which have yet to sign the CTBT—has been lagging, compared to the pace in the other signatory countries.

In addition, nearly half of China’s stations have not yet been certified by the CTBTO Preparatory Committee.223

At the CTBT Scientific and Technical Conference in June 2023, the United States introduced its efforts and contributions to the detection and verification of nuclear explosive tests.224 In an effort primarily aimed at reducing tensions with Russia and China, at the IAEA General Conference in late September, the United States proposed reciprocal visits to nuclear test sites as a means to uphold the moratorium on nuclear test explosions.225 In addition, the U.S. Nevada National Security Site (NNSS) conducted a subsurface chemical explosion to improve the U.S. ability to detect low-yield nuclear explosions around the world. The National Nuclear Security Administration (NNSA) also reported: “The experiment will help validate new predictive explosion models and detection algorithms. Measurements were collected using accelerometers, seismometers, infrasound sensors, electromagnetic sensors, chemical and radiotracer samplers, and meteorological sensors.”226
In the meantime, while Russia revoked its ratification of the CTBT, Russian Ministry of Defense announced in November that Russia’s segment of the international network that monitors under the CTBT would be completed in 2023.227

 

E) Nuclear testing

No country conducted a nuclear test explosion in 2023. In its annual report on “Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments” published in April 2023, the U.S. State Department again alleged that China and Russia may have conducted nuclear tests in previous years that created nuclear yield, contrary to the common understanding that the CTBT standard is “zero yield.”228 Both China and Russia strongly denied the U.S. allegations, stating that they have not conducted any nuclear tests that would violate the CTBT.

Meanwhile, in February 2023, Vyacheslav Solovyov, scientific director of the Russian Federal Nuclear Centre said that Russia was ready to resume testing at the Novaya Zemlya nuclear test site if necessary.229 In his address to the Federal Assembly in February, President Putin also ordered preparations for the resumption of nuclear testing, and said, “We will not be the first to do this, but if the USA conducts [nuclear] tests, then we will also conduct them.”230 In September, satellite images reportedly showed that China, Russia and the United States have been expanding their respective underground nuclear test sites.231

Regarding experimental activities other than nuclear test explosions, the United States continues to conduct various non-explosive tests and experiments under the Stockpile Stewardship Program (SSP), to sustain and evaluate its nuclear weapons stockpile without the use of underground nuclear tests. These include subcritical tests and experiments using the Z machine, which generates X-rays by fast discharge of capacitors, thus allowing for exploring the properties of plutonium materials under extreme pressures and temperatures. The NNSA reported that it planned to conduct two subcritical experiments in fiscal year 2024 (October 2023-September 2024),232 but as of the end of 2023, this was not reported to have taken place.

While France and Russia and the United Kingdom have engaged in subcritical experiments and other activities that do not lead to nuclear explosions, there have been no specific instances reported in 2023. The other nuclear armed-states have not released any information regarding whether they have conducted nonexplosive testing activities.

While the CTBT does not prohibit any nuclear test unaccompanied by an explosion, the NAM countries argued:

[T]he Group is of the firm view that all States parties that have not yet done so should close and dismantle, as soon as feasible and in a transparent, irreversible and verifiable manner, any remaining sites and laboratories for nuclear test explosions and their associated infrastructure, and prohibit completely nuclear weapons research and development, and also refrain from conducting nuclear weapon test explosions or any other nuclear explosions, or nuclear weapon test explosions in alternative ways, including simulation and subcritical testing, as well as the use of new technologies for upgrading the existing nuclear weapons system, which would defeat the object and purpose of the Comprehensive Nuclear-Test-Ban Treaty.233

Contrasting with the CTBT, which explicitly prohibits any nuclear test “explosions,” the TPNW broadly bans “nuclear tests,” a term that could be interpreted to include even those tests that do not result in an explosion. Meanwhile, the TPNW does not specify measures for verifying compliance with this testing ban.

 

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212 “Putin Orders Army to Prepare for Nuclear Tests, Saying US Is Creating New Weapons,” Ukrainska Pravda, February 21, 2023. https://www.pravda.com.ua/eng/news/2023/02/21/7390282/.
213 “Putin Says Russia Has Tested Next-Generation Nuclear Weapon,” Reuters, October 6, 2023, https:// www.reuters.com/world/europe/putin-says-russia-has-tested-next-generation-nuclear-weapon-2023-10-05/.
214 “Russian Lawmakers to Consider De-Ratifying Nuclear Test Ban Treaty,” Moscow Times, October 6, 2023, https://www.themoscowtimes.com/2023/10/06/russian-lawmakers-to-consider-de-ratifying-nucle ar-test-ban-treaty-a82681.
215 “Russia Will Revoke Ratification of Nuclear Test Ban Treaty, Envoy Says,” Guardian, October 7, 2023, https://www.theguardian.com/world/2023/oct/06/nuclear-watchdog-russia-putin-testing-treaty.

216 “Final Declaration and Measures to Promote the Entry Into Force of the CTBT,” September 22, 2023.
217 “Convening the Regional Meeting to Promote the Entry into Force of the CTBT,” Ministry of Foreign Affairs of Japan, July 7, 2023, https://www.mofa.go.jp/mofaj/press/release/press5_000063.html. (in Japanese)
218 A/RES/78/66, December 4, 2023.

219 CTBT-Art.XIV/2023/4, August 28, 2023.

220 “Report on 5th Plenary Meeting of 7th C.C., WPK,” NCNK, January 1, 2020, https://www.ncnk.org/ resources/publications/kju_2020_new_years_plenum_report.pdf/file_view.
221 Colin Zwirko, “North Korea Hints at ‘Resuming’ Long-Range Weapons Tests after New US Sanctions,” NK News, January 20, 2022, https://www.nknews.org/2022/01/north-korea-hints-at-resuming-long-range-weapons-tests-after-new-us-sanctions/.
222 CTBTO, “Status of Assessed Contributions,” December 31, 2023, https://www.ctbto.org/sites/ default/files/2024-01/20231231_Status%20of%20Assessed%20Contribution_0.pdf.

223 CTBTO, “Station Profiles,” https://www.ctbto.org/verification-regime/station-profiles/.

224 “Remarks by NNSA Deputy Administrator for Defense Nuclear Nonproliferation Corey Hinderstein at the CTBT: Science and Technology Conference 2023,” NNSA, June 20, 2023, https:// www.energy.gov/nnsa/articles/remarks-nnsa-deputy-administrator-defense-nuclear-nonproliferation-corey-hinderstein.
225 Jonathan Tirone, “US Offers Nuclear-Test Inspections to Ease Russia, China Tension,” Bloomberg, September 29, 2023, https://www.bloomberg.com/news/articles/2023-09-28/us-throws-nuclear-arms-control-a-life-preserver-at-iaea-meeting.
226 “NNSA Conducts Experiment to Improve U.S. Ability to Detect Foreign Nuclear Explosions,” NNSA, October 18, 2023, https://www.energy.gov/nnsa/articles/nnsa-conducts-experiment-improve-us-ability-detect-foreign-nuclear-explosions-0.
227 “Russia Says It’s Completing Its Section of International Nuclear Test Monitoring Network,” Reuters, November 17, 2023, https://www.reuters.com/world/europe/russia-says-its-completing-its-section-inter national-nuclear-test-monitoring-2023-11-17/.
228 The U.S. Department of State, Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments, April 2023.

229 “‘We Are Ready’: Novaya Zemlya Range Ground Ready to Resume Nuclear Tests,” Pravda, February 8, 2023, https://english.pravda.ru/news/russia/155726-russia_novaya_zemlya/.
230 Tetiana Lozovenko, “Putin Orders Army to Prepare for Nuclear Tests, Saying US Is Creating New Weapons,” Ukrainska Pravda, February 21, 2023, https://www.pravda.com.ua/eng/news/2023/02/21/ 7390282/.
231 Eric Cheung, Brad Lendon and Ivan Watson, “Satellite Images Show Increased Activity at Nuclear Test Sites in Russia, China and US,” CNN, September 23, 2023, https://edition.cnn.com/2023/ 09/22/asia/nuclear-testing-china-russia-us-exclusive-intl-hnk-ml/index.html. In December, it was also reported that China has been intensifying its activities, including the excavation of new tunnels. William J. Broad, Chris Buckley, and Jonathan Corum, “China Quietly Rebuilds Secretive Base for Nuclear Tests,” The New York Times, December 20, 2023, https://www.nytimes.com/interactive/2023/12/20/science/ china-nuclear-tests-lop-nur.html.
232 “Remarks by NNSA Deputy Administrator for Defense Nuclear Nonproliferation Corey Hinderstein at the CTBT: Science and Technology Conference 2023,” NNSA, June 20, 2023, https://www.energy. gov/nnsa/articles/remarks-nnsa-deputy-administrator-defense-nuclear-nonproliferation-corey-hinderstein.

233 NPT/CONF.2026/PC.I/WP.9, June 14, 2023.