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Hiroshima for Global Peace

(7) CTBT

(7) CTBT

A) Signing and ratifying the CTBT

As of December 2019, 168 of the 184 signatories have deposited their instruments of ratification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Zimbabwe ratified in 2018. 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 2019 NPT PrepCom, Russia blamed U.S. attitudes toward the CTBT, and opposed the provisional application of the treaty.177

As for efforts to promote CTBT entry into force during 2019, the 11th Conference on Facilitating the Entry into Force of the CTBT (Article XIV Conference) was held at the UN headquarters on September 25, 2019. In its final declaration, participating countries reaffirmed the importance of the CTBT for nuclear disarmament and non-proliferation; urged to sign and ratify it as soon as possible and maintain a moratorium on nuclear testing; and listed concrete and practical measures for facilitating the early entry into force of the CTBT.178

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,”179 distributed at the Article XIV Conference, 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, UAE, the United Kingdom and others);
➢ Global-level activities (conducted by Belgium, Brazil, Germany, Japan, Mexico, New Zealand, Philippines, Russia, 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.

North Korea, at the Plenary Meeting of the Central Committee of the Workers’ Party of Korea on May 20, 2018, decided to withhold nuclear and ICBM testing, and shut down its Punggye-ri nuclear test site. Since this announcement, North Korea has continued not to conduct nuclear test explosions. However, it is not clear whether or not the nuclear test site was irreversibly destroyed. North Korea is considered to be able to reuse the Punggye-ri nuclear test site after weeks or months of restoration work.180 In addition, at the fifth Plenary Meeting of the seventh Central Committee of the Workers’ Party of Korea held in late December 2019, Chairman Kim reportedly told that there was no ground for North Korea to get unilaterally bound to its commitment of halting nuclear (and missile) tests.181

C) Cooperation with the CTBTO Preparatory Commission

Regarding the countries surveyed in this study, the status of payments of contributions to the CTBTO, as of 2019, is as follows.182
➢ Fully paid: Australia, Austria, Belgium, Canada, China, France, Germany, Indonesia, Israel, Japan, Kazakhstan, South Korea, Netherlands, New Zealand, Norway, Philippines, Poland, Russia, South Africa, Sweden, Switzerland, Turkey, UAE, the United Kingdom and the United States
➢ Partially paid: None
➢ Not Paid: Chile and Egypt
➢ Voting right in the Preparatory Commission suspended because arrears are equal to or larger than its contributions due for the last two years: Brazil, Iran and Nigeria After an explosion at a Russian military test site in August 2019, the CTBTO reported that some of its radionuclide monitoring stations close to the test site went offline and halted transmissions.183 Russia insisted to the CTBTO that the accident in August had no connection to CTBTO’s activities, and said, “It’s essential to keep in mind that handing over data from our national stations which are part of the international monitoring system is entirely voluntary for any country.”184

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 China, Egypt and Iran—in addition to those of 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.185

In June 2019, the fifth CTBT Science and Technology Conference was held to discuss the technical aspects of detection and verification of nuclear tests.186

E) Nuclear testing

No country conducted a nuclear test explosion in 2019. North Korea, which carried out six tests from 2006 to 2017, announced that it no longer needed a nuclear test and nuclear test site in 2018 due to completion of its development of nuclear forces.

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, such as 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 U.S. NNSA had released quarterly reports on such experiments, but as of December 2019 has not updated it since the first quarter of FY 2015. Meanwhile, the United States announced that it would conduct two subcritical experiments per year beginning in FY 2020.187 In February 2019, it conducted a subcritical test, named “EDIZA Vega,” which was the U.S.’s 29th subcritical experiment since the moratorium on nuclear test explosion went into effect in 1992.188 In this experiment, the steel containment vessel cracked, and a small amount of plutonium leaked.189 The U.S. NNSA plans to procure the world’s most powerful supercomputer by late 2023 for the purpose of running simulations of nuclear weapon examinations for maintaining their safety and reliability.190

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.”191 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 2010.192 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. Meanwhile, it was reported that China, which has aggressively developed its next generation of nuclear weapons, carried out around 200 laboratory experiments (an average of five tests a month) between September 2014 and 2018 to simulate the extreme physics of a nuclear blast, using a large, sophisticated facility known as a multi-stage gas gun, which simulates the extreme heat, pressure and shock waves produced in a real nuclear blast.193 In December 2018, China was also reported to have built a Chinese version of the U.S. “Z machine.”194

Regarding Russia, Director of the U.S. DIA Robert Ashley stated at a meeting in May 2019, “The United States believes that Russia probably is not adhering to its nuclear testing moratorium in a manner consistent with the ‘zero-yield’ standard.” It assesses that Russia conducted clandestine very low-yield nuclear tests on the Arctic island of Novaya Zemlya.195 The DIA reaffirmed his statement the following month and issued a statement saying, “The U.S. government, including the Intelligence Community, has assessed that Russia has conducted nuclear weapons tests that have created nuclear yield. Regarding China, the information raised at the Hudson Institute, coupled with China’s lack of transparency on their nuclear testing activities, naturally raise questions about those activities in relation to the “zero yield” nuclear weapons testing moratorium.196 In response, Russia strongly denied the U.S. claims, saying, “We are acting in full and absolute accordance with the[CTBT] and in full accordance with our unilateral moratorium on nuclear tests.”197 The CTBTO also issued a statement as following: “The CTBTO has full confidence in the ability of the IMS to detect nuclear test explosions according to the provisions of the Comprehensive Nuclear-Test-Ban Treaty (CTBT).”198

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.199 Different from the CTBT, which prohibits any nuclear test “explosion,” the TPNW bans “nuclear tests,” which can be interpreted to mean that it bans tests that do not produce an explosion. On the other hand, the TPNW does not stipulate measures for verifying the testing ban. 

177 NPT/CONF.2020/PC.III/WP42, April 26, 2019.

178 “Final Declaration and Measures to Promote the Entry into Force of the Comprehensive Nuclear-Test-Ban Treaty,” September 25, 2019.

179 CTBT-Art.XIV/2019/4, September 5, 2019.

180 “(2nd LD) N. Korea Able to Use Punggye-ri Nuke Testing Site after Restoration Work: JCS,” Yonhap News Agency, October 8 2019,

181 “Report on 5th Plenary Meeting of 7th C.C., WPK,” KCNA, January 1, 2020,

182 CTBTO, “CTBTO Member States’ Payment as at 31-Dec-2019,”

183 Francois Murphy, “Global Network’s Nuclear Sensors in Russia Went Offline after Mystery Blast,” Reuters, August 19 2019,

184 Andrew Osborn, Maria Kiselyova, “Russia to Nuclear Test Ban Monitor: Test Accident Not Your Business,” Reuters, August 20, 2019,

185 CTBTO, “Station Profiles,”

186 CTBTO, “CTBT Science and Technology 2019 Conference,” September 24-28, 2019,

187 NNSA, Fiscal Year 2020 Stockpile Stewardship and Management Plan, July 2019, p. 8-11.

188 Nolan O’Brien, “Subcritical Experiment Captures Scientific Measurements to Advance Stockpile Safety,” Lawrence Livermore National Laboratory, May 24, 2019,

189 Kathy Crandall Robinson, “Subcritical Nuclear Tests Raise New Dangers,” Tri-Valley CAREs, May 9, 2019,

190 “This New Supercomputer Will be the World’s Most Powerful; Will Simulate Nuclear Explosions,” Computer Business Review, August 13, 2019,

191 NPT/CONF.2015/PC.III/14, April 25, 2014.

192 NPT/CONF.2015/29, April 22, 2015.

193 Stephen Chen, “China Steps Up Pace in New Nuclear Arms Race with US and Russia as Experts Warn of Rising Risk of Conflict,” South China Morning Post, May 28, 2018,

194 Stephen Chen, “Operation Z Machine: China’s Next Big Weapon in the Nuclear ‘Arms Race’ Could Create Clean Fuel—Or Deadly Bombs,” South China Monitoring Post, December 12, 2018,

195 Robert P. Ashley, Jr., “Russian and Chinese Nuclear Modernization Trends,” Remarks at the Hudson Institute, May 29, 2019, See also Daryl G. Kimball, “U.S. Questions Russian CTBT Compliance,” Arms Control Today, July/August 2019, p. 20.

196 Defense Intelligence Agency, “DIA Statement on Lt. Gen. Ashley’s Remarks at Hudson Institute,” June 13, 2019,

197 Daryl G. Kimball, “U.S. Claims of Illegal Russian Nuclear Testing: Myths, Realities, and Next Steps,” Arms Control Association, August 21, 2019,

198 CTBTO, “Media Statement by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (in response to media reports quoting remarks by U.S. Lieutenant General Robert P. Ashley),” May 29, 2019,

199 NPT/CONF.2020/PC.III/WP.16, March 21, 2019.

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