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Hiroshima for Global Peace

Hiroshima Report 2023(8) CTBT

A) Signing and ratifying the CTBT

As of the end of 2022, 176 of the 186 signatories have deposited their instruments of ratification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT).

Among the 44 states listed in Annex 2 of the CTBT, ratification of which is a prerequisite for the treaty’s entry into force, five states (China, Egypt, Iran, Israel 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. The draft final document of the NPT RevCon stated, “States Parties commit to pursue the urgent entry into force of the [CTBT] urge all States that have yet to ratify the CTBT to do so in all expediency, particularly the remaining eight States listed in its Annex 2 and recall the special responsibility of nuclear weapon States in this regard as stipulated in Action 10 of the 2010 Action Plan.”

On September 22, Prime Minister Kishida hosted the High-Level Meeting of the Friends of the CTBT, which had been held in alternate years at ministerial level, with the aim of bringing the CTBT into force as soon as possible. In his speech at the meeting, Prime Minister Kishida stated, “We will once again clarify our strong commitment to the universalization of the CTBT and its early entry into force, and we will advance concrete efforts to this end.” He called for the CTBT’s verification regime to be strengthened, and expressed the view that Japan would make an even greater contribution. He also stated that, as a specific effort, Japan would further actively support both ratifying and non-ratifying countries, especially in the Asia-Pacific region, in developing and strengthening the operational framework of the CTBT; and it would also maintain and strengthen monitoring facilities, including those located in Japan, and further enhance the international monitoring system.268 In the joint statement of the meeting, participating countries called for, inter alia, early signature and ratification of the CTBT by countries that have not yet done so, especially those that are required for entering into force; expressed any new North Korean nuclear test would be unacceptable; called for maintaining the moratorium on nuclear tests; welcomed for efforts to complete the CTBT verification system; and appealed for increased public awareness, including youth, of the CTBT and its importance at the highest political level.269

At the 2022 UNGA, a resolution, titled “Comprehensive Nuclear-Test-Ban Treaty,” 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 179 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 2019-May 2021,” 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, Austria, Belgium, Canada, Japan, Kazakhstan, New Zealand, Russia, Switzerland, the United Kingdom and others); 

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

➢Global -level activities (conducted by Australia, Austria, Canada, Japan, Kazakhstan, New Zealand, Russia, Switzerland, the United Kingdom and others)
➢ Global-level activities (conducted by Australia, Austria, Canada, Japan, Kazakhstan, New Zealand, Russia, Switzerland, the United Kingdom and others)

➢Regional-level activities (conducted by Australia, New Zealand, Russia 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. 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 intermediate-range missiles and ICBMs. 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 ICBM tests.272 In January 2022, Chairman Kim instructed the area concerned to reconsider the moratorium on ICBM launch tests and nuclear explosion tests, and to examine the issue on resuming them promptly.273

The IAEA Director-General Report in September 2022, titled “Application of Safeguards to DPRK,” indicated that North Korea is vigorously refurbishing and upgrading its nuclear test site in preparation for a resumption of nuclear explosion testing by North Korea, stating the following:

In early-March 2022, excavation work commenced near Adit 3 at the nuclear test site located near the settlement of Punggye-ri, to reopen the test tunnel after its partial demolition in May 2018. Excavation work at Adit 3 was possibly completed by May 2022.82 Several timber support buildings were constructed concurrently near the entrance to Adit 3, and also in the support area located to the north.83 The Agency observed work during June 2022 to shore up portions of the washed-out road that led from the support area to Adit 4 and Adit 2. After several weeks of inactivity, the road construction had resumed by late-August 2022.274

Earlier in May, Kim Tae-hyo, First Deputy Director of the National Security Office of the South Korean Presidential Office, revealed an analysis that North Korea was in the final stage of preparing for a nuclear test, as it had been detected that North Korea was repeatedly conducting operational tests of its detonation devices. U.S. Special Representative for North Korea Son Kim also said in a telephone press conference on June 7, “North Korea has completed its preparations for a nuclear test. It can conduct a test at any time.” However, North Korea did not conduct a nuclear test explosion in 2022.


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, 2022, is as follows:275

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

➢Voting right in the Preparatory Commission suspended because arrears are equal to or larger than its contributions due for the last two years: Brazil and 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 its national report submitted to the NPT RevCon, China stated, “In recent years, a significant number of nuclear test-ban monitoring stations have been accepted for certification in China, constituting a highlight in building the verification regime for the [CTBT]. … The acceptance for certification of that group of stations in China and their commencing data transmission was a significant milestone, reflecting firm Chinese support for the preparation of a verification regime for the Comprehensive Nuclear-Test-Ban Treaty.”276 However, nearly half of its stations have not yet been certified by the CTBTO Preparatory Committee.277


E) Nuclear testing

No country conducted a nuclear test explosion in 2022. In its annual report on “Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments” published in April 2022, 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.”278 Both China and Russia strongly denied the U.S. allegations, stating that they have not conducted any nuclear tests that would violate the CTBT.

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 United States has conducted subcritical experiments at a rate of about once a year. In June and September 2021, it conducted such tests under the names Nightshade B and Nightshade C.279 The U.S. National Nuclear Security Administration (NNSA) released quarterly reports on such experiments, but has not published any updates it since the first quarter of FY 2015. In addition, after 2018, past information could not be found on the NNSA homepage.

Among nuclear-armed states apart from the United States, Russia’s Ministry of Defense announced in June 2021 that it had conducted subcritical experiments to verify the reliability of its existing nuclear weapons.280 France clarified that it has conducted “activities aimed at guaranteeing the safety and reliability of its nuclear weapons [including] a simulation program and hydrodynamic experiments designed to model materials’ performance under extreme physical conditions and, more broadly, the weapons’ functioning.”281 However, there are no further reports about whether France conducted such experiments during 2022. Meanwhile, France and the United Kingdom agreed to build and jointly operate radiographic and hydrodynamic testing facilities under the Teutates Treaty concluded in November 2010.282

Although the status of the remaining nuclear-armed states’ nonexplosive testing activities in this respect is not well known since they have not released any information, it was reported that China has a facility under construction, with the capacity to surpass the U.S. Z machine, and that it was expected to be completed soon.283 In addition, satellite images show that China has been expanding its nuclear testing facility at Lop Nur, which some analysts believe would allow for nuclear weapons-related testing.284

While the CTBT does not prohibit any nuclear test unaccompanied by an explosion, the NAM countries have demanded, inter alia, that nuclear-armed states refrain from conducting nuclear weapon test explosions or any other nuclear explosions, and to close and dismantle—in a transparent, irreversible and verifiable manner—any remaining sites for nuclear test explosions and their associated infrastructure.285 They also stated at the NPT RevCon, “The nuclear-weapon States stated at that time that the only steps to be followed would be to maintain the safety and reliability of the remaining or existing weapons, which would not involve nuclear explosions. In that regard, the Group calls upon those States to continue to refrain from conducting any type of nuclear test for the modernization, development or further improvement of nuclear weapons.”286 Unlike the CTBT, which prohibits any nuclear test “explosions,” the TPNW bans “nuclear tests,” which can be interpreted to ban even those tests that do not produce an explosion. On the other hand, the TPNW does not stipulate measures for verifying the testing ban.


268 “The 10th High-Level Meeting of the Friends of the Comprehensive Nuclear Test Ban Treaty (CTBT),” Prime Minister’s Office of Japan, September 21, 2022, statement/2022/0921ctbt.html. (in Japanese)
269 “Joint Statement on the Comprehensive Nuclear-Test-Ban Treaty,” Ministry of Foreign Affairs of Japan, September 21, 2022,
270 A/RES/77/94, December 7, 2022.

271 CTBT-Art.XIV/2021/4, September 22, 2021.

272 “Report on 5th Plenary Meeting of 7th C.C., WPK,” NCNK, January 1, 2020, resources/publications/kju_2020_new_years_plenum_report.pdf/file_view.
273 Colin Zwirko, “North Korea Hints at ‘Resuming’ Long-Range Weapons Tests after New US Sanctions,” NK News, January 20, 2022,

274 GOV/2022/40-GC(66)/16, September 7, 2022.

275 CTBTO, “Status of Assessed Contributions,” December 31, 2022, default/files/2023-01/20221231_Status%20of%20Assessed%20Contributions.pdf.

276 NPT/CONF.2020/41, November 16, 2021.
277 CTBTO, “Station Profiles,”
278 The U.S. Department of State, Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments, April 2022.

279 U.S. Department of Energy Office of Scientific and Technical Information, “Operational and Mission Highlights: A Monthly Summary of Top Achievements July 2021,” August 12, 2021, https://www.osti. gov/biblio/1813824; U.S. Department of Energy Office of Scientific and Technical Information, “Operational and Mission Highlights: A Monthly Summary of Top Achievements October 2021,” October 1, 2021,
280 Isaac Evans, “Russia Conducts Non-Nuclear Tests, Adhering to UN Treaty,” The Organization for World Peace, June 29, 2021,

281 NPT/CONF.2015/PC.III/14, April 25, 2014.
282 NPT/CONF.2015/29, April 22, 2015.
283 Michael Peck, “China Will Soon Have Its Own Z Machine to Test Mock Nuclear Explosions,” National Interest, August 15, 2020, chine-test-mock-nuclear-explosions-166995.
284 “Satellite Photos Show China’s New Nuclear Test Site in Xinjiang,” Nikkei Asia, August 15, 2022,

285 NPT/CONF.2020/PC.III/WP.16, March 21, 2019. The prefectural governments and city halls of Hiroshima and Nagasaki have also condemned the subcritical experiments.
286 NPT/CONF.2020/WP.21, November 22, 2021.


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