In their joint statement submitted to the NPT PrepCom, Austria, Mexico, Norway and the United Kingdom raised the following issues related to the concept of irreversibility in nuclear disarmament.261

Efforts to understand irreversibility, like transparency and verification, are not an end in themselves. They are not a pre-requisite to commence nuclear disarmament, in compliance with the spirit and letter of article VI of the NPT. Nor are they a pre-requisite to implement the obligations and commitments agreed within the framework of the treaty. We are convinced that the implementation of these obligations and commitments will benefit from work already having been done on these three principles, and ensuring the implementation to be more effective and sustainable.
We reiterate the central importance of applying the agreed principles of transparency, verifiability, and irreversibility to any nuclear disarmament efforts, and towards the sustainability of all pillars of the NPT.
We are, therefore, supportive of enhanced dialogue among States parties to build a common understanding of the application of irreversibility, in its technical, legal, normative and political dimensions.

We also highlight that while all states have an interest in attaining and maintaining a world without nuclear weapons, the main focus of such a dialogue would be on irreversibility in the actions and activities of nuclear-weapon States to implement their agreed obligations and commitments on nuclear disarmament. This actions and activities [sic] will benefit from work already having been done on the three principles.
Moreover, we also acknowledge that nuclear disarmament efforts become significantly more irreversible when they are underpinned by a legally-binding obligation on the total elimination of nuclear weapons.
Nuclear disarmament should be irreversible as all states parties of the NPT are concerned about the catastrophic consequences that would arise from the use of such weapons.

In addition, several projects were undertaken at the initiative of the United Kingdom to promote dialogues among international experts and practitioners on irreversibility.262

 

A) Implementing or planning dismantlement of nuclear warheads and their delivery vehicles

As with their previous nuclear arms control agreements, the New START obliges Russia and the United States to dismantle or convert strategic (nuclear) delivery vehicles beyond the limits set in the treaty, and to do so in a verifiable way. The New START does not require the dismantlement of retired nuclear warheads, but the two states have partially dismantled retired nuclear warheads as unilateral measures. As mentioned above, in 2021, the Biden administration declassified the number of dismantled U.S. nuclear warheads. According to a State Department fact sheet, the United States dismantled 184 nuclear warheads in 2020, and 11,638 warheads from 1994 through 2020.263 On the other hand, it is also pointed out that the pace of nuclear warhead dismantlement by the United States has slowed significantly.264

The other NWS did not release any information regarding nuclear weapons dismantlement in 2021. However, France and the United Kingdom have dismantled their retired nuclear warheads and delivery vehicles. France also mentioned, in its national report submitted to the NPT RevCon in 2022, that it had begun dismantling its M4 SSBN.265

 

 

B) Decommissioning/conversion of nuclear weapons-related facilities

No remarkable activity or progress was reported in 2023 in terms of decommissioning or converting nuclear weapons-related facilities. In its working paper submitted to the NPT PrepCom, the EU “[called] on all States that have not done so to ‘initiate a process towards the dismantling or conversion for peaceful uses of facilities for the production of fissile material for use in nuclear weapons or other nuclear explosive devices.’”266

In 1996, France became the only country to decide to completely and irreversibly dismantle its nuclear test sites, which were fully decommissioned in 1998.267 In its national report submitted to the NPT RevCon, France reported that it has engaged in decommissioning operations for the former fissile material production facilities for nuclear weapons, including its uranium enrichment facility, reprocessing facility and plutonium production reactor.268 The United States also reported the following: “In 1980, the nuclear complex was made up of 14 sites. Today, it consists of eight, and its workforce has been reduced by two-thirds since the end of the Cold War.”269

 

C) Measures for fissile material declared excess for military purposes, such as disposition or conversion to peaceful purposes

In October 2016, Russian President Putin issued a Presidential Decree on suspending implementation of the Russian-U.S. Plutonium Management and Disposition Agreement (PMDA), which entered into force in July 2011.270 This situation has not been resolved.

In the meantime, as mentioned in the Hiroshima Report 2021, the United States formally terminated construction of the Mixed Oxide Fuel Fabrication Facility (MFFF) at the Savannah River Site in South Carolina in 2018. The NNSA has proposed to repurpose the MFFF to produce plutonium pits.

Meanwhile, South Africa criticized the NWS’s activities, stating:

Even if all civilian materials were safeguarded and fully secured to the highest standards, this would only cover an estimated 15% of the weapons-usable material around the world, leaving a critical gap in the nuclear non-proliferation architecture. Hence, we should not lose sight of the remaining 85%, which is categorized as military materials and are not subject to any international security standards or oversight mechanisms.
It is regrettable that little progress has been made to implement the actions agreed to at the 2010 NPT RevCon in the development of appropriate legally-binding verification arrangements with the IAEA to ensure the irreversible removal of fissile material designated by each nuclear-weapon State as no longer required for military purposes. Neither has there been progress with regard to additional declarations of stockpiles of fissile material that could be used in nuclear weapons or other nuclear explosive devices. To the contrary, the Safeguards Implementation Report 2022 reflects that some [NWS] have withdrawn such material.271

The NAC also said, “[It] calls for the implementation by the nuclear-weapon States of the agreed commitment to declare to the International Atomic Energy Agency all fissile material designated as no longer required for military purposes and to place such material, as soon as practicable, under safeguards.”272

 

 

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261 “Joint Statement of Norway on behalf of Austria, Mexico, Norway and the United Kingdom,” Cluster 1, First PrepCom for the 11th NPT RevCon, August 3, 2023.

262 See, for instance, “Irreversibility of Nuclear Disarmament,” Verification Research, Training and Information Centre (VERTIC), https://www.vertic.org/programmes/vm/irreversibility-of-nuclear-disar mament/.
263 NNSA, “Transparency in the U.S. Nuclear Weapons Stockpile.”
264 Hans M. Kristensen and Matt Korda, “Nuclear Notebook: United States Nuclear Weapons, 2023,” Bulletin of the Atomic Scientists, January 16, 2023, https://thebulletin.org/premium/2023-01/nuclear-notebook-united-states-nuclear-weapons-2023/.

265 NPT/CONF.2020/42/Rev.1, August 1, 2022.
266 NPT/CONF.2026/PC.I/WP.4, June 6, 2023.
267 NPT/CONF.2015/10.
268 NPT/CONF.2020/42/Rev.1, August 1, 2022.
269 NPT/CONF.2020/47, December 27, 2021.
270 This decree stipulates, inter alia, that 34 tons each of surplus U.S. and Russian plutonium extracted from dismantled nuclear warheads shall be converted into mixed oxide (MOX) fuel for use in civilian nuclear reactors.

271 “Statement of South Africa,” Cluster 2, First PrepCom for the 11th NPT RevCon, August 7, 2023.

272 NPT/CONF.2026/PC.I/WP.5, June 13, 2023.