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Hiroshima for Global Peace

(7) CTBT

A) Signing and ratifying the CTBT

As of the end of 2020, 168 of the 184 signatories have deposited their instruments of ratification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). No country ratified it in 2020. Among the 44 states listed in Annex 2 of the CTBT, whose ratification 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 even signed. Among the countries surveyed, Saudi Arabia and Syria have not signed the CTBT either.

At the 2020 UNGA, a resolution, titled “Comprehensive Nuclear-Test-Ban Treaty,”184 in which member states “[stress] the vital importance and urgency of signature and ratification, without delay and without conditions, in order to achieve the earliest entry into force of the [CTBT],” was adopted with 182 countries in favor, two against (North Korea and the United States) and three abstentions (India, Syria and others). As for efforts to promote CTBT entry into force, the biennial Ministerial Meeting of the Friends of the CTBT in 2020 could not be convened due to the COVID-19 pandemic. However, Foreign Ministers of the Friends of CTBT (Australia, Canada, Finland, Germany, Japan and the Netherlands) released respective video messages and press releases on October 1, in which they called for the entry into force of the CTBT.185 Among them, Japanese Foreign Minister Toshimitsu Motegi stated, “Since the dawn of this century, almost all states have observed a moratorium on nuclear testing. Worldwide condemnation against North Korea’s nuclear tests demonstrates the strengthened sense of norm against nuclear testing. We must promote the entry into force of the CTBT and strengthen its monitoring capabilities to deter nuclear tests.”186

Regarding outreach activities for promoting the treaty’s entry into force, a document, “Activities Undertaken by Signatory and Ratifying States Under Measure (K) of the Final Declaration of the 2015 Article XIV Conference in the Period June 2017-May 2019,”187 distributed at the Article XIV Conference on Facilitating the Entry-Into-Force of the CTBT, summarized activities conducted by ratifying and signatory states. It highlighted:

➢ Bilateral activities related to Annex 2 states (conducted by Austria, Belgium, Germany, Japan, Mexico, New Zealand, Russia, the United Kingdom and others);
➢ Bilateral activities related to non-Annex 2 states (conducted by Austria, Belgium, Japan, Mexico, New Zealand, Russia, the UAE, the United Kingdom and others);
➢ Global-level activities (conducted by Belgium, Brazil, Germany, Japan, Mexico, New Zealand, the Philippines, Russia, the UAE, the United Kingdom and others)
➢ Regional-level activities (conducted by Belgium, Germany, Japan, Mexico, New Zealand 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.

Meanwhile, in May 2020, U.S. senior officials in charge of security issues reportedly discussed the resumption of nuclear explosive testing, but were unable to reach a conclusion due to opposition from the NNSA, among other reasons.188 U.S. Deputy Assistant Secretary of Defense Drew Walter emphasized that there “has been no policy change” regarding its moratorium on nuclear testing, but also said that the United States could conduct nuclear test explosion within a month if ordered by the president for technical or geopolitical reasons.189 Commander of the U.S. Strategic Command Charles Richard also said at the U.S. Senate Armed Services Committee in September, “At this time, there is no condition…where I would recommend the need for nuclear testing. … But I would say though that it is important for the nation to maintain an ability to do a nuclear test should an issue arise in the future, and I’ve been formally documented in making that recommendation.”190

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. The next months, North Korea collapsed the entrances to its Punggye-ri nuclear test site. 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” of stopping nuclear and ICBM tests.191 While North Korea did not resume nuclear test explosions in 2020, it is not clear whether or not its nuclear test site was irreversibly destroyed. Rather, it is considered to be able to reuse the Punggye-ri nuclear test site after weeks or months of restoration work.192

C) Cooperation with the CTBTO Preparatory Commission

Regarding the countries surveyed in this study, the status of contribution payments to the CTBTO, as of December 31, 2020, is as follows:193

➢ Fully paid: Australia, Austria, Belgium, Canada, China, Egypt, France, Germany, Indonesia, Israel, Japan, Kazakhstan, the Netherlands, New Zealand, Norway, the Philippines, Poland, Russia, Sweden, Switzerland, Turkey, the UAE, the United Kingdom, the United States
➢ Partially paid: South Korea
➢ Not Paid: Mexico 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: Brazil, Chile, Iran and Nigeria

D) Contribution to the development of the CTBT verification systems

The establishment of the CTBT verification system has steadily progressed. 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 behind, compared to that in the other signatory countries.194 As for China, more than half of the stations have not yet been certified by the CTBTO Preparatory Committee. The United States also pointed out that China has frequently blocked the flow of data from its IMS stations to the CTBTO.195 China denied the allegation, and criticized the United States.196

E) Nuclear testing

No country conducted a nuclear test explosion in 2020.

Meanwhile, in its annual report on “Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments” published in June 2020, the U.S. State Department alleged that China and Russia may have conducted nuclear tests which created nuclear yield, in violation of the CTBT that prohibits nuclear test explosions as “zero yield.”197 On Russia, “The United States assesses that Russia has conducted nuclear weapons-related experiments that have created nuclear yield. The United States does not know how many, if any, supercritical or self-sustaining nuclear experiments Russia conducted in 2019. Russia may be testing in a manner that releases nuclear energy from an explosive canister, which raises compliance concerns with Russia’s [Threshold Test Ban Treaty] notification obligation.”198 The report also mentioned that “China’s possible preparation to operate its Lop Nur test site year-round, its use of explosive containment chambers, extensive excavation activities at Lop Nur, and lack of transparency on its nuclear testing activities – which has included frequently blocking the flow of data from its [IMS] stations to the International Data Center operated by the Preparatory Commission for the [CTBTO]—raise concerns regarding its adherence to the ‘zero yield’ standard adhered to by the United States, the United Kingdom, and France in their respective nuclear weapons testing moratoria.”199 Both China and Russia strongly denied the U.S. allegations, stating that they have not conducted any nuclear tests that would violate the CTBT.200

Regarding experimental activities other than a nuclear explosion test, the United States continues to conduct various nonexplosive tests and experiments under the Stockpile Stewardship Program (SSP), in order to sustain and assess its nuclear weapons stockpile without the use of underground nuclear tests. These include subcritical tests and experiments using the Z machine, which generates Xrays by fast discharge of capacitors, thus allowing for exploring the properties of plutonium materials under extreme pressures and temperatures. The U.S. NNSA released quarterly reports on such experiments, but has not updated it since the first quarter of FY 2015. In addition, after 2018, past information could not be found on the NNSA homepage.

The United States continues to conduct subcritical experiments, and has announced its intention to conduct such experiments twice a year starting in fiscal year 2020.201 In November 2020, personnel at the Los Alamos National Laboratory conducted a subcritical experiment, named “Nightshade A,” at the Nevada National Nuclear Security Site. It was the third subcritical experiment under the Trump administration, and the first one since 2019. This test was said to be the first of three consecutive tests, whose stated purpose is to obtain “important information to improve weapons physics.”202

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.”203 However, no further details were reported. Meanwhile, France and the United Kingdom agreed to build and jointly operate radiographic and hydrodynamic testing facilities under the Teutates Treaty concluded in November 2010.204 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 a China’s facility under construction, with the capacity to surpass the U.S. Z machine, was expected to be completed soon.205

While the CTBT does not prohibit any nuclear test unaccompanied by an explosion, the NAM countries have demanded that nuclear-armed states, inter alia, 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.206 As opposed to the CTBT, which prohibits any nuclear test “explosions,” the TPNW bans “nuclear tests,” which can be interpreted to ban even those nuclear tests that do not produce an explosion. On the other hand, the TPNW does not stipulate measures for verifying the testing ban.

184 A/RES/75/87, December 7, 2020.
185 “‘Friends of the CTBT’ Group Issues Video Call for Treaty’s Entry into Force,” October 1, 2020, entry-into-force/.
186 “Message by Foreign Minister Motegi for the Friends of the CTBT,” October 1, 2020, https://www.
187 CTBT-Art.XIV/2019/4, September 5, 2019.
188 Jon Hudson and Paul Sonne, “Trump Administration Discussed Conducting First Nuclear Test in Decades,” Washington Post, May 23, 2020,
189 Aaron Mehta, “Live Nuclear Testing Could Resume in ‘Months’ If Needed, Official Says,” Defense News, May 26, 2020,
190 Rebecca Kheel, “Top Admiral: ‘No Condition’ Where US Should Conduct Nuclear Test ‘at This Time,’” Hill, September 17, 2020,
191 “Report on 5th Plenary Meeting of 7th C.C., WPK,” NCNA, January 1, 2020,
192 “(2nd LD) N. Korea Able to Use Punggye-ri Nuke Testing Site after Restoration Work: JCS,” Yonhap News Agency, October 8, 2019,
193 CTBTO, “CTBTO Member States’ Payment as at 31-Dec-2020,”
194 CTBTO, “Station Profiles,”
195 The U.S. Department of State, “Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments,” June 2020, p. 50.
196 “Foreign Ministry Spokesperson Zhao Lijian’s Regular Press Conference,” April 16, 2020,
197 This report also mentioned: “Official statements from senior officials of all the NWS, including Russia and China, expressed these states’ interpretation that CTBT’s scope was ‘zero-yield.’ What precisely this meant, however, was less clear, since no written agreement on the definition of ‘zero-yield’ was reached.” The U.S. Department of State, “Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments,” June 2020, p. 48.
198 Ibid., p. 46.
199 Ibid., p. 47.
200 “Foreign Ministry Spokesperson Zhao Lijian’s Regular Press Conference,” April 16, 2020,; “Statement by Russia,” First Committee, UNGA, October 9, 2020.
201 NNSA, Fiscal Year 2020 Stockpile Stewardship and Management Plan, July 2019, pp. 8-11.
202 Los Alamos National Laboratory, Operational and Mission Highlights: A Monthly Summary of Top Achievements, November 2020, pp. 1-2.
203 NPT/CONF.2015/PC.III/14, April 25, 2014.
204 NPT/CONF.2015/29, April 22, 2015.
205 Michael Peck, “China Will Soon Have Its Own Z Machine to Test Mock Nuclear Explosions,” National Interest, August 15, 2020,
206 NPT/CONF.2020/PC.III/WP.16, March 21, 2019.

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