US-UK Mutual Defence Agreement A Nuclear Information Service Briefing 1 2 US-UK Mutual Defence Agreement A Nuclear Information Service Briefing Second Edition Nuclear Information Service October 2024 3 NIS Contents Nuclear Information Service (NIS) is an independent, Introduction 5 not-for-profit research organisation, founded in 2000. History of the MDA 6 We investigate the UK nuclear weapons programme The Treaty 8 and publish accurate and reliable information to Activities under the MDA 10 stimulate informed debate on disarmament and Nuclear Testing 10 related issues. Transfer of nuclear material 11 Transfer of non-nuclear components 11 Joint Working Groups and Secondment 12 Legality 13 Future of the MDA 13 Annotated Treaty text 16 Endnotes 28 4 Introduction This briefing gives an overview of the Agreement between the Government of the United Kingdom of Great Britain and Northern Ireland and the Government of the United States of America for Cooperation on the Uses of Atomic Energy for Mutual Defense Purposes, commonly known as the Mutual Defence Agreement (MDA). The MDA is the treaty that governs the relationship between the nuclear weapons programmes of the United Kingdom (UK) and United States (US), which is unique amongst nuclear armed states for the level of dependency and technical integration involved. The treaty allows for the exchange of information about nuclear technologies between the two states, and for the US to provide the UK with nuclear materials, such as uranium and plutonium, components of nuclear weapons, and submarine reactor technology. Staff from the nuclear enterprises in both countries coordinate activities through Joint Working Groups and are sometimes seconded to work in the other country for some time. Until 1992, cooperation under the MDA included use of each others’ sites for nuclear testing, particularly the UK testing nuclear weapons in Nevada. 5 lGO/llirreM nAiluJ )tOHP(AOP :tiderC The UK currently operates a submarine-launched nuclear weapons system. The reactors that power the UK’s four nuclear-armed submarines, and other submarine technologies on board, are based on US designs. The UK’s warheads are believed to be very close in design to weapons in the US stockpile. US designed and manufactured Trident missiles carry the UK’s warheads. The UK’s use of the Trident system is governed by an updated version of the Polaris Sales Agreement, which is a separate treaty from the MDA. In 2014 David Lidington, a UK Foreign Office Minister, said the treaty ‘helps to provide the maintenance and servicing required to ensure the safety, security and reliability’ of the UK’s nuclear weapons ‘at a substantial reduction on the costs that would otherwise be incurred’.1 An amendment to the treaty, published in 2024, will extend sharing of nuclear material and other components under the MDA indefinitely. This edition of the briefing has been updated to take into account the proposed 2024 changes. HMS Victorious, one of the UK’s nuclear-armed submarines, alongside at Faslane in 2007. History of the MDA2 The UK and US worked together on the Manhattan uranium 235 for civil use, more intelligence sharing Project, which produced the first nuclear weapons. and joint nuclear war planning. Uranium 235 is the The basis for nuclear cooperation during the Second highly radioactive isotope used in reactor fuel and World War was the 1943 Quebec Agreements and the nuclear weapons. An agreement on the UK being 1944 Hyde Park aide memoire. Both were executive supplied with nuclear submarine technology followed agreements between Churchill and Roosevelt, rather in 1956. than treaties, and were not subject to Congressional approval. The UK’s production capacity for aircraft capable of carrying nuclear weapons soon outstripped the speed After the use of nuclear weapons in Hiroshima and at which it could produce nuclear material for the Nagasaki, the US Congress, which was not aware weapons themselves. Informal discussions began in of the extent of UK involvement in the Manhattan 1957 on the US providing highly enriched uranium Project, passed the 1946 McMahon Act. The act (HEU) to allow the UK to increase its stockpile faster, prevented US citizens from sharing information about although the transfers were not permitted under the nuclear weapons with foreign nationals, immediately 1954 Act. curtailing cooperation with the UK.3 The UK’s nuclear weapons at this time were all Due to differing interpretations of the Act amongst US fission designs, utilising the destructive power of a government agencies some collaboration on intelligence critical mass of fissile material, compressed using sharing and uranium supply continued to take place. As explosives. Modern US and UK weapon designs are the Cold War began to take hold, US nuclear bombers thermonuclear weapons where the energy from a were also deployed in the UK, and the practicalities of fission weapon, made of uranium 235 or plutonium, military cooperation would in time place a strain on the is used as a ‘primary’ to implode a ‘secondary’: a fuel strict conditions of the McMahon Act. which undergoes nuclear fusion, releasing an even greater destructive power. The UK had responded to the Act by deciding to develop its own nuclear weapons. The US, at the time The UK producing its own independent thermonuclear still the only nuclear-armed state, made a proposal weapons is often portrayed as the trigger for the in 1948 for a resumed integrated nuclear weapons US deciding that it was willing to resume nuclear programme which would have seen the UK having cooperation,4 but this is not the case. The UK carried custody of a stockpile of 20 nuclear bombs. A similar out tests on thermonuclear weapons in May and June proposal was floated in 1953, following the UK’s first 1957, but the tests were not successful. At the time nuclear test in 1952, but the two states did not come to the US was publicly calling for an international ban an agreement. The UK was the third state to develop on both nuclear testing and the further production its own nuclear weapons, the Soviet Union having of nuclear weapons, in response to domestic and carried out a nuclear test in 1949. international protests against atmospheric testing. The UK was keen to produce a working thermonuclear In 1954 the McMahon Act was replaced with the design before this happened. After the thermonuclear Atomic Energy Act, a compromise which allowed tests failed the UK told the US it would only support exchanges of knowledge for civil nuclear purposes the proposed ban if it had independent access to a and allowed some basic information about the yields stockpile of modern weapon designs. and military characteristics of US nuclear weapons to be shared with NATO states. This would allow these The launch of the Sputnik satellite in October 1957 states, including the UK, to field delivery systems changed the political environment, as it demonstrated for the weapons. A new UK-US agreement in 1955, that Soviet rocket technology could theoretically brokered under the new regime, covered the supply of launch a nuclear weapon as far as the continental 6 Canadian Prime Minister Mackenzie King, President Franklin D Roosevelt and Winston Churchill during the Quebec Conference, 18 August 1943. Canada hosted the conference but was not party to the Quebec Agreement. US. A US-UK leaders’ summit was quickly arranged, were set aside to allow matters to progress. President which resulted in the US National Security Council Eisenhower eventually signed an updated Atomic approving a full exchange of information and a Energy Act in July 1958 and the MDA was signed the commitment from the US to amend the 1954 Act. following day. While discussions were ongoing about the shape of future cooperation, the UK carried out a successful test The treaty has been repeatedly amended since 1958, of a thermonuclear design in November 1957. often to extend the time period for sharing nuclear material and non-nuclear components. Other changes The MDA reflected the priorities of both states, but show the treaty changing to reflect the realities of the it more closely resembles the form envisaged by the working relationship. Regular ‘stocktake’ meetings are US at the beginning of negotiations. Congressional held to discuss and plan the functioning of the treaty.5 hearings on amending the 1954 Act began in early 1958, The 2024 amendments suggest that future changes but controversies around an exchange of plutonium are likely to be managed through implementing and HEU, and a proposal for nuclear warheads under agreements, rather than regular changes to the treaty.6 joint US-UK control, meant that these measures 7 MuesuM rAW lAirePMi :tiderC The Treaty The initial form of the treaty allowed for the sharing of intelligence and sale of a submarine reactor and fuel to the UK, covered in Article II and Article III of the treaty respectively. Despite its prominence in bilateral discussions leading up to the treaty, the transfer of complete nuclear weapons between the two states was explicitly prohibited in the treaty text. An amendment to the treaty in 1959 added Article III bis, which enabled the transfer of nuclear material and non-nuclear components of nuclear weapons, but initially only for a 10-year period. Most of the amendments to the treaty have extended this period, and between 1984 and 2024 the extensions have were for additional periods of 10 years. Other amendments also made more substantial changes to the treaty. In 1984, the first amendment after the US sale of the Trident missile system to the UK had been agreed, text was added enlarging the scope of information sharing under the treaty and to allow for the transfer of enriched uranium for any purpose.7 In 2014 the amendments added a reference to the dangers of proliferation in the preamble, and allowed for the UK to purchase more submarine reactors, reactor parts and fuel.8 Smaller amendments have also been made, for example in 1994 a change was made to allow the US to arrange uranium enrichment for the UK, rather than directly providing it,9 and in 2014 a paragraph was amended to include evaluating the capabilities of enemy states as one of the permitted purposes for information sharing.10 Facing page: Mushroom cloud from the US Dominic Truckee nuclear test, 9 June 1962, Kiritimati. 8 seviHCrA lAnOitAn su The 2024 amendments are the most significant changes to the the treaty since the 1950s. Of the 13 articles in the treaty, 12 have been amended in some way, with five being completely replaced with new versions. The most substantial change is the removal of the sunset clause for sharing of nuclear materials and non-nuclear components, but other changes allow the UK to supply reactors, parts and fuel to the US, and for any kind of naval reactor to be transferred. Many of the changes are relatively small, however, such as simplifying language, rectifying stylistic inconsistencies, and referencing modern information classification categories. The changes also explicitly rule out the use of external dispute settlement mechanisms and allow for implementing agreements, suggesting that these will be used instead of future treaty amendments. An annotated text of the treaty, including the 2024 amendment can be found on page 16 of this briefing. The treaty is written using US English spellings. 9 seviHCrA lAnOitAn su Nuclear Testing Although one of the drivers for the treaty was concern about a ban on nuclear testing,11 access to testing facilities was one of the UK’s priorities in the original negotiations. After the 1958 moratorium on nuclear testing was breached by the USSR in 1961, the UK and US both resumed testing, with the UK carrying out tests at the Nevada Test Site (NTS), and the US carrying out most of their Dominic test series in Kiritimati (then known as ‘Christmas Island’),12 which was at that time a British colonial holding. The UK carried out 24 underground tests at the NTS between 1962 and 1991. The final test, known as ‘Julin/ Bristol’, is believed to have been testing the lower-yield variant of the UK Trident warhead.13 The US Dominic test series involved 25 atmospheric nuclear tests at or near Kiritimati.14 Indigenous people in both Nevada15 and Kiritimati,16 and armed forces veterans,17 are still dealing with the consequences of nuclear tests. Craters from underground nuclear tests at Yucca Flat, in the Nevada Test site. 10 Asnn :tiderC Activities under the MDA Since 1992 both states have observed a moratorium on nuclear testing and have signed the Comprehensive Nuclear Test Ban Treaty, however the US has not ratified the treaty. Both the UK and US have active development and research programmes and are upgrading their nuclear weapons systems. This work does not involve live testing of nuclear weapons, but instead research using high energy lasers, computer simulation and sub-critical tests, which only use smaller quantities of fissile material than the amount needed to reach a critical mass. Through the MDA the UK and US research programmes are deeply intertwined and many of their research facilities have been designed to be complementary.18 The vast majority of countries worldwide have expressed concerns about countries upgrading their nuclear weapons.19 Figure A. Transfer of non-nuclear components under the MDA 2020–2023 Calendar year Transfers from US to UK (single items) Transfers from UK to US (single items) 2020 128 14 2021 271 25 2022 302 31 2023 254 38 Total 955 108 Transfer of nuclear material Transfer of non-nuclear components The acquisition of nuclear material from the US was There is little information in the public domain about a major initial goal for the UK, and the purchase of the quantity and nature of transfers of non-nuclear HEU for submarine reactors and tritium for nuclear components under the MDA. It is known that the weapons took place soon after the treaty was signed. Mk4A upgrade to the UK’s nuclear warhead, completed Subsequently, barter exchanges of nuclear material in 2023, involved changing the arming, fusing and were carried out between 1960 and 1979, with the UK firing system, neutron initiators and the gas transfer sending plutonium in exchange for HEU and tritium. system, with these components being imported The UK sent 0.5 tonne of plutonium to the US between from the US.22 The submarine reactor used in the 1960 and 1969 under Barter A, 4.1 tonnes between 1964 current Astute and Vanguard nuclear submarines is and 1969 under Barter B and 0.8 tonne between 1975 and a UK-specific design and may only use domestically 1979 under Barter C. In return, the UK received a total of produced parts. However, the PWR3 reactor used in 6.7kg of tritium and 7.5 tonnes of HEU from the US.20 the forthcoming Dreadnought submarines is based on a US design23 and it is possible that some parts for Transfers of plutonium also took place outside of these reactors are being imported under the MDA. these disclosed barter arrangements, with a total of 0.47 tonne being sent from AWE Aldermaston to the In response to a Freedom of Information Request US and received back prior to March 1999. The timing by NIS the MOD stated that transfers of non- of these plutonium ‘loans’ and in which direction the nuclear parts of nuclear weapon systems under the initial transfer took place has not been disclosed.21 MDA between 2020 and 2023 had amounted to 955 individual items being transferred from the US to the No information about plutonium transfers after UK and 108 individual items being transferred from March 1999 or transfers of HEU and tritium outside the UK to the US.24 The breakdown of these transfers the three barter exchanges has been made public, by year can be found in Figure A. and the MOD has rejected Freedom of Information Requests for information about more recent transfers. However, the 2014 amendments to the MDA and nuclear road convoy movements suggest that transfer of HEU fuel for UK submarines is ongoing. The UK and US also have a joint programme to calibrate their nuclear forensic laboratories by testing the same samples, and the transfer of nuclear material in these samples is likely also carried out under the MDA. 11 Joint Working Groups and Secondment The primary method for US-UK cooperation under the MDA is through Joint Working Groups (JOWOGs). These are thematic committees comprised of subject matter experts from the nuclear enterprises of both countries. Each JOWOG focusses on a particular research area that has been identified during stocktake meetings and meets periodically. JOWOG meetings include presentations on specific areas of research, but can also agree research priorities, review progress and determine how work should be divided between Warhead handling during the US W76-1 warhead upgrade, different agencies or laboratories. which involved many components used in the UK Mk4A upgrade. Figure B shows the activity of JOWOGs since 1959. Initially 15 JOWOGs were created, but most of these have been retired as their remit was no longer deemed relevant. At least 48 JOWOGs have been created since 1959, and 15 are currently active, as of June 2024.25 Some JOWOGs appear to have been retired and reactivated at a later date, but this seems to be comparatively rare. Some of the JOWOGs have subcommittees for further specialisation within the subject area. These are known as SUBWOGs. Figure B shows the JOWOGs known to have been active at different times during the operation of the MDA. Of the original 15, only one is known to still be active: JOWOG 9, which coordinates research on ‘Energetic Materials’, meaning explosives. Some JOWOGs have undergone name changes over the years. The titles of two of the original 15 JOWOGs have been partially redacted. The full title of JOWOG 2 appears to have been ‘500 to 600-pound megaton warhead’.26 Of the 15 JOWOGs currently active, the MOD refused to disclose the names of six.27 As a consequence it is not clear whether the JOWOGs looking into ‘Radiation Simulation and Kinetic Effects’, ‘Warhead Electrical Components and Technologies’, ‘Nuclear Counter- Terrorism Technology’, ‘Aircraft, Missile and Space System Hardening’, and ‘Methodologies for Nuclear Weapon Safety Assurance’ are still active. The title of JOWOG 47 has not been made public,28 and it can be surmised that at least one other new JOWOG has been created since 2009. One or more of these new groups are probably working on the planned 12 tnAlP xetnAP :tiderC new US W93 and UK Astrea warheads, which have been described as ‘parallel’ projects, and their re-entry bodies. Aside from JOWOGs the two states also arrange Exchange of Information by Visit Report, which are one-off information exchange events and Channels, which are more often used for management coordination and the exchange of regular information.29 Between 2007 and 2009 over 2,000 visits by AWE staff were made to US nuclear facilities.30 Secondment of staff from one state to the nuclear enterprise of the other also takes place, building up reciprocal knowledge and allowing for deployment of specific expertise. In response to a Freedom of Information request in June 2024 the Atomic Weapons Establishment (AWE) said that the numbers of its employees seconded to the US and of US employees seconded to AWE was ‘very low’, so disclosing the actual numbers risked identifying individuals.31 In response to a parliamentary question in 2018 the government said that 43 employees of the US government and General Dynamics Electric Boat company were seconded with the Dreadnought programme and 20 UK government employees working on the Dreadnought programme were seconded to the US.32 Legality Future of the MDA A 2004 legal advice prepared by Rabinder Singh The 2014 amendment to the MDA extended the sunset QC and Professor Christine Chinkin said it was clause for Article III bis until December 31 2024. The ‘strongly arguable’ that the role of the MDA in the amendment published in July 202436 removes the UK’s ongoing nuclear weapons programme was a sunset clause from Article III bis to extend sharing breach of the country’s obligations under the Nuclear of non-nuclear components and nuclear materials Non-Proliferation Treaty (NPT), under which the indefinitely. nuclear-armed states agreed to eliminate their nuclear weapons.33 Under the 2010 Constitutional Reform and Governance Act the UK Government has to publish any treaty The position of the UK government, as stated in a 2014 it plans to ratify, and Parliament has 21 days within parliamentary debate, is that the MDA does not breach which it can vote to block ratification, potentially the NPT because it prohibits transfer of complete indefinitely. This time limit only includes days when nuclear weapons and only allows for the transfer of Parliament is sitting, so the deadline for passing a knowledge and weapon components between two resolution objecting to the the amendment is 23rd nuclear-weapon states. At the time it was also stated October 2024.37 that the UK was complying with its obligations under the NPT by reducing the numbers of its nuclear The amendment will also need to be approved by the weapons.34 However, since then government policy has US Congress before it can come into force. President changed and in 2021 a planned reduction in the UK’s Biden wrote to the House of Representatives in July stockpile to 180 warheads was reversed and instead the endorsing the amendment.38 In September, legislation stockpile size was increased to 260.35 was introduced to approve the amendment.39 At the time of writing, in early October 2024, the amendment seems likely to gain legislative assent in both the US and UK. The new provisions for implementing agreements in the 2024 amendment suggest that the two states plan to use this mechanism for future changes to the treaty, instead of amendments. These would be unlikely to be subject to the same level of legislative scrutiny. Nuclear Information Service calls for full scrutiny of the amendment in both nations through select committee hearings and/or debates. The indefinite extension of US-UK nuclear sharing runs contrary to the disarmament commitments of both states under the Nuclear Non-Proliferation Treaty. The primary focus of the transatlantic nuclear relationship should be on fulfilling those commitments instead of avoiding them. 13 JOWOG 1959 1973 1995 1997 1998 2002 2009 2024 Antimissile missile defence 1 systems 500 to 600-pound [redacted] 2 warhead 3 150-pound [redacted] warhead Methods of predicting one-point 4 detonation yields 5 External neutron sources Neutron sources Irradiation effects on materials Irradiation effects on materials 6 Radiation Simulation and Kinetic Effects Technology and components and components 7 Mixing in gas-boosted weapons 8 Shock-initiation of explosives 9 Safety of HMX explosives Energetic Materials Nonnuclear and hydrodynamic 10 testing Analysis and specification of 11 materials* Chemistry and Compatability of 12 Compatability of materials materials Underground and outer space 13 testing 14 Weapons effects for future tests 15 Joint test facilities 16? Test Diagnostics 17? Test monitoring 18? Metallurgy of Weapons Materials 19? Non-Nuclear Components 20? Underground Effects Testing 21? Non-Metallic Materials 22 Nuclear Materials 23 Warhead Electrical Components and Technologies ? Weapons Material Management 28 Non-Nuclear Materials 29 Nuclear Counter-Terrorism Technology Infrastructure and Operational 30 Facilities Support 31 Nuclear Weapons Engineering 32 Physics Design Nuclear Warhead Physics 33 Weapons Hydrodynamics 34 Computational Technology 35 Penetration Aid Technology 36 Aircraft Hardening Aircraft, Missile and Space System Hardening 37 Nuclear Weapons Physics Laboratory Plasma Physics Nuclear Forces and Counter 38 Proliferation Studies 39 Manufacturing Technology 40 Experimental Activities 41 Nuclear Warhead Accident Response Technology Nuclear Weapon Computer Code 42 Nuclear Weapon Code Development Development 43 Nuclear Weapon Environment and Damage Effects Methodologies for Nuclear 44 Weapon Safety Assurance 45 Defense Penetrability Knowledge, Information 46 Management and Classification 47 48 Radiochemistry and Nuclear Data 14 ? 044202–9591 spuorG gnikroW tnioJ evitcA .B erugiF JOWOG 1959 1973 1995 1997 1998 2002 2009 2024 Antimissile missile defence 1 systems 500 to 600-pound [redacted] 2 warhead 3 150-pound [redacted] warhead Methods of predicting one-point 4 detonation yields 5 External neutron sources Neutron sources Irradiation effects on materials Irradiation effects on materials 6 Radiation Simulation and Kinetic Effects Technology and components and components 7 Mixing in gas-boosted weapons 8 Shock-initiation of explosives 9 Safety of HMX explosives Energetic Materials Nonnuclear and hydrodynamic 10 testing Analysis and specification of 11 materials* Chemistry and Compatability of 12 Compatability of materials materials Underground and outer space 13 testing 14 Weapons effects for future tests 15 Joint test facilities 16? Test Diagnostics 17? Test monitoring 18? Metallurgy of Weapons Materials 19? Non-Nuclear Components 20? Underground Effects Testing 21? Non-Metallic Materials 22 Nuclear Materials 23 Warhead Electrical Components and Technologies ? Weapons Material Management 28 Non-Nuclear Materials 29 Nuclear Counter-Terrorism Technology Infrastructure and Operational 30 Facilities Support 31 Nuclear Weapons Engineering 32 Physics Design Nuclear Warhead Physics 33 Weapons Hydrodynamics 34 Computational Technology 35 Penetration Aid Technology 36 Aircraft Hardening Aircraft, Missile and Space System Hardening 37 Nuclear Weapons Physics Laboratory Plasma Physics Nuclear Forces and Counter 38 Proliferation Studies 39 Manufacturing Technology 40 Experimental Activities 41 Nuclear Warhead Accident Response Technology Nuclear Weapon Computer Code 42 Nuclear Weapon Code Development Development 43 Nuclear Weapon Environment and Damage Effects Methodologies for Nuclear 44 Weapon Safety Assurance 45 Defense Penetrability Knowledge, Information 46 Management and Classification 47 48 Radiochemistry and Nuclear Data ? 15 Annotated Treaty text41 Reference to the United Kingdom Atomic Energy The Government of the United Kingdom of Great Britain and Northern Ireland and the Authority (UKAEA) Government of the United States of America, (collectively, the “Parties”), removed in 1974. C onsidering that their mutual security and defense require that they be prepared to ‘The Parties’ was used meet the contingencies of atomic warfare; in the treaty but not C onsidering that both countries have made substantial progress in the specified before this 2024 development of atomic weapons; addition. Reaffirming that the spread of atomic weapons technology, potentially including State and sub-State actors, imperils the defense and security of both nations; Text added to preamble Considering that they are participating together in international arrangements in 2014 referencing pursuant to which they are making substantial and material contributions to their proliferation risks. mutual defense and security; Recognizing that: their common defense and security will be advanced by the exchange of information concerning atomic energy and by the transfer of equipment and materials for use therein; Believing that such exchange and transfer can be undertaken without risk to the defense and security of either country; and Taking into consideration the United States Atomic Energy Act of 1954, as amended, which was enacted with these purposes in mind, Have agreed as follows: 16 ARTICLE I General Provision While the United States and the United Kingdom are participating in an international arrangement for their mutual defense and security and making substantial and material contributions thereto, each Party will communicate to and exchange with the other Party information, and transfer materials and equipment to the other Party, in accordance with the provisions of this Agreement provided that the originating Party determines that Terminology simplified such cooperation will promote and will not constitute an unreasonable risk to its defense in 2024. and security. ARTICLE II New 2024 version of Article II includes Exchange of Information more detailed language on information A. Each Party will communicate to or exchange with the other Party such Atomic classification categories, Information and other related: Classified Information, Controlled Unclassified the clarification about Information, technical data and technology subject to either Party’s export control nuclear security and requirements, Sensitive Nuclear Technology and Controlled Nuclear Information, as is threat reduction, and jointly determined to be necessary to: paragraph C. Previous 1. t he development of defense plans; changes in 1984 2. t he training of personnel in the employment of and defense against atomic increased the scope of weapons and other military applications of atomic energy; sharing and the types of 3. t he evaluation of the capabilities of potential enemies in the employment of information shared. atomic weapons and other military applications of atomic energy; 4. t he development of delivery systems compatible with the atomic weapons which they carry; and 5. research, development or design of military reactors. For the avoidance of doubt, the Parties understand the above-mentioned purposes to incorporate security of the nuclear security enterprise and support of nuclear threat reduction capabilities. B. In addition to the cooperation provided for in paragraph A of this Article, each Party will exchange with the other Party Atomic Information concerning atomic weapons and other related: Classified Information, Controlled Unclassified Information, technical data and technology subject to either Party’s export control requirements, Sensitive Nuclear Technology, Controlled Nuclear Information, and special nuclear materials properties and production or processing technology, when, after consultation with the recipient Party, the originating Party determines that the communication of such information is necessary to improve the recipient Party’s atomic weapon design, development or fabrication capability. C. In addition to the provisions of this Agreement, the originating Party shall apply its internal processes to the communication or exchange of information to the recipient Party. 17 ARTICLE III New 2024 version of Article III allows for Naval Nuclear Propulsion Plants and Related Equipment, Information and reciprocal transfer of Materials reactors, parts and fuel, and allows transfer of A. Subject to terms and conditions acceptable to it, an originating Party may directly, or any naval reactor, not may authorize persons to: just submarine reactors. 1. t ransfer by sale to the recipient Party or persons designated by the recipient Party A previous change in naval nuclear propulsion plants or parts thereof, including spare parts, naval 2014 amended the 1958 reactor cores, fuel elements and other related equipment, as may be agreed by text allowing sale of the Parties; and a single submarine 2. c ommunicate to or exchange with the recipient Party or persons designated by the reactor to allow sale of recipient Party information, including information designated as Naval Nuclear multiple reactors or parts Propulsion Information (“NNPI”), as is necessary for the research, development of reactors. The 2024 or design of naval nuclear propulsion plants or parts thereof, including their version keeps most of manufacture, operation, maintenance, regulation and disposal. the 2014 changes, but removes a paragraph on B. Each Party may transfer to the other Party agreed amounts of materials, including legal indemnification U-235 contained in uranium enriched in the isotope U-235, as needed for use in any naval and adds reactor nuclear propulsion plant on such terms and conditions as may be agreed. If the Parties regulation and disposal, mutually agree to do so, the originating Party may reprocess any material transferred plus new grounds for under this paragraph in facilities of the originating Party, on terms and conditions to information sharing. be agreed, or may authorize such reprocessing in private facilities in the territory of the originating Party. Enriched uranium recovered in reprocessing such materials by either Party may be purchased by the originating Party under terms and conditions to be agreed. Special nuclear material recovered in reprocessing such materials and not purchased by the originating Party may be returned to or retained by the recipient Party. C. Each Party shall be compensated for enriched uranium sold by it pursuant to this Article at a price based on the fair market price of comparable enriched uranium at the time of the sale. For types of enriched uranium that do not have a commercial market, compensation for sale will be made at a price to be agreed by both Parties. D. The Parties may communicate or exchange information, including NNPI, on methods of reprocessing fuel elements of the type utilized in any naval nuclear propulsion plant, including information on the design, construction or operation of facilities for the reprocessing of such fuel elements. ARTICLE III BIS Article III bis was added to the treaty in 1959 and Transfer of Materials and Equipment contains the operative text for the transfer of A. The Government of the United States shall transfer to the Government of the non-nuclear components United Kingdom the following in such quantities, at such times, and on such terms and and nuclear material. conditions as may be agreed: 1. n on-nuclear parts of atomic weapons which parts are for the purpose of improving Amendments in 2024 the United Kingdom’s state of training and operational readiness; removed the sunset 2. o ther non-nuclear parts of atomic weapons systems involving Restricted Data clause from Article III bis which parts are for the purpose of improving the United Kingdom’s state of training and operational readiness when in accordance with appropriate requirements of applicable laws; 18 3. s ource, by-product and special nuclear material, and other material, for research on, development of, or use in atomic weapons when, after consultation with the Government of the United Kingdom, the Government of the United States In 1968 the reference determines that the transfer of such material is necessary to improve the United to ‘other material’ was Kingdom’s atomic weapon design, development or fabrication capability. added, and this text moved to a separate B. The Government of the United States shall transfer to the Government of the United paragraph. ‘Utilization Kingdom special nuclear material, and authorize the transfer of other material, for research facility’ is a technical on, development of, production of, or use in utilization facilities for military applications, term for a nuclear in such quantities, at such times, and on such terms and conditions as may be agreed. reactor. C. The Government of the United States shall transfer enriched uranium to the New paragraph in 1984 Government of the United Kingdom, and shall arrange enrichment and other uranium allowed for enriched services for the Government of the United Kingdom, for military purposes, in such uranium transfers for quantities, at such times, and on such terms and conditions as may be agreed. any purpose, instead of just improving weapon D. The Government of the United Kingdom shall transfer to the Government of the design or fabrication. United States for military purposes such source, by-product, other material and special nuclear material, and equipment of such types, in such quantities, at such times, and on Text amended in 1994 such terms and conditions as may be agreed. to allow for the US to arrange enrichment E. 1. W ith respect to by-product material, special nuclear material and other material for the UK as well as transferred from one Party to the other under this Article, the recipient Party providing it directly. agrees not to use any such material for purposes other than those for which it was received, provided that material which has lost its identity as a result of Several minor textual commingling with other material of the recipient Party may be put to other uses changes made in 2024 if the recipient Party retains an equivalent amount of its own material for the purpose for which the originating Party’s material was received. 2. F or material or equipment transferred from one Party to the other Party, the recipient Party shall pay or reimburse, as may be agreed, all packaging, transportation and related costs. Packaging, shipping containers and methods of shipment shall be as may be agreed. 3. S hould either Party desire to acquire materials or components for use in the manufacture or in preparation for manufacture of atomic weapons from any source within the jurisdiction of the other Party, the procuring Party shall inform the other Party of the proposed procurement in order that such other Party may determine whether the proposed procurement involves information communicated or exchanged pursuant to this Agreement and if so whether the proposed procurement is in compliance with its applicable laws and regulations. ARTICLE IV Responsibility for Use of Information, Material and Equipment and Waiver of Article updated in 2024 Claims with some minor textual changes and adding the A. The application or use of any information (including design drawings and waiver in the title. specifications), material or equipment communicated, exchanged or transferred under this Agreement shall be the responsibility of the recipient Party, and the originating Party does not provide any indemnity, and does not warrant the accuracy or completeness of such information and does not warrant the suitability or completeness of such information, material or equipment for any particular use or application. 19 B. The recipient Party waives all of its claims, except contract claims, against Paragraph B added in the originating Party and its employees, arising out of or connected with the use or 2024. application of this information, material or equipment, including any claim arising out of or connected with the design, manufacture, assembly, transfer or utilization of naval nuclear propulsion plants, spare parts, naval reactor cores or fuel elements transferred pursuant to this Agreement. ARTICLE V Conditions A. Cooperation under this Agreement will be carried out by each of the Parties in Several minor edits were accordance with its applicable laws and regulations. made in 2024 to clarify the text of Article V. B. Under this Agreement there will be no transfer by either Party of atomic weapons. Paragraph C rewritten in C. Except where specifically authorized by this Agreement or as may be agreed for civil 1979 to allow other uses uses, the recipient Party agrees not to use the information communicated or exchanged, under the agreement. or the materials or equipment transferred, pursuant to this Agreement for other than the preparation or implementation of defense plans, including the evaluation of potential Text including enemy capabilities, in the mutual interests of the two countries. evaluation of enemy capabilities added in 2014 D. Nothing in this Agreement shall preclude the communication or exchange of Classified Information, Controlled Unclassified Information, technical data and Updated paragraph D technology subject to either Party’s export control requirements, Sensitive Nuclear in 2024 includes greater Technology or Controlled Nuclear Information, which may be transmitted under other detail on information arrangements between the Parties. classification categories, and mention of export ARTICLE VI control requirements. A 1984 amendment Guaranties had previously added information categories. A. Classified Information communicated or exchanged, as well as materials and equipment transferred, pursuant to this Agreement shall be accorded full security Amendments in 2024 protection under applicable security arrangements between the Parties and applicable to clarify text and laws and regulations of the Parties. In no case shall either Party maintain security add greater detail standards for safeguarding Classified Information, materials or equipment made on information available pursuant to this Agreement less restrictive than those set forth in the applicable classification categories security arrangements in effect on the date this Agreement comes into force. Additions in 1984 B. Controlled Unclassified Information, technical data and technology subject to either including protections Party’s export control requirements, Sensitive Nuclear Technology and Controlled for nuclear technology, Nuclear Information communicated or exchanged pursuant to this Agreement shall be nuclear material and accorded at least the same level of protection by the recipient Party as that accorded controlled information, to such information by the originating Party. The Parties shall consult with each other alongside the original regarding the appropriate protections for such information. protection for classified information. C. Classified Information designated by the United Kingdom as “OFFICIAL- SENSITIVE” shall be protected by the United States in accordance with the procedures New paragraph added in identified in an implementing instrument or instruments entered into by the Parties. 2024. 20 D. Adequate physical security shall be maintained with respect to any source material, Amendment in 2024 special nuclear material and equipment transferred pursuant to the Agreement, and replaced previous with respect to any special nuclear material used in or produced through the use of any wording that linked material or reactor so transferred. Each Party shall provide protection commensurate protections to the with both Parties’ laws, regulations and policies. importance of material or equipment. E. Information communicated or exchanged pursuant to this Agreement will be made available through channels existing or hereafter agreed for the communication or Amendments in 2024 exchange of such information between the Parties. substituted this catch- all term for a longer list F. Information communicated or exchanged, and any materials or equipment transferred, of information types. pursuant to this Agreement shall not be communicated, exchanged or transferred by the Several of these had been recipient Party or persons under its jurisdiction to any unauthorized persons, or, except added in in 1984. as provided in Article VII of this Agreement, beyond the jurisdiction of that Party. Each Party may stipulate the degree to which any of the information, materials or equipment communicated, exchanged or transferred by it or persons under its jurisdiction pursuant to this Agreement may be disseminated or distributed; may specify the categories of persons who may have access to such information, materials or equipment; and may impose such other restrictions on the dissemination or distribution of such information, materials or equipment as it deems necessary. G. Adequate materials control and accountability shall be maintained with respect to Paragraph on controlling any nuclear material (including source material and special nuclear material) transferred and accounting for pursuant to the Agreement, and with respect to any nuclear material used in or produced nuclear materials added through the use of any nuclear material or equipment transferred pursuant to the in 1994. Agreement. Each Party guarantees adequate materials control and accountancy shall be maintained so long as such nuclear material or equipment remains under its jurisdiction or control. As may be mutually agreed, the Parties shall consult with each other regarding methods and technology for providing such materials control and accountability. ARTICLE VII New 2024 version of Article VII retains the Dissemination of Information, Materials and Equipment meaning of the previous version but uses Nothing in this Agreement shall be interpreted or shall operate as a bar or restriction updated terminology to consultation or cooperation in any field of defense by either Party with other commensurate with nations or international organizations. Neither Party, however, shall communicate or other 2024 changes. exchange information or transfer or permit access to or use of materials or equipment Previously, more detail made available by the originating Party pursuant to this Agreement to any nation or on sharing with other international organization unless: states and international organistions had been A. it is notified by the originating Party that all appropriate provisions and requirements added in 1959 and of the originating Party’s applicable laws and regulations, including authorization by additional information competent bodies of the originating Party, have been complied with as necessary to categories in 1984. authorize the originating Party directly so to communicate to, transfer to or permit access to or use by such other nation or international organization; and further that the originating Party authorizes the recipient Party so to communicate to, transfer to or permit access to or use by such other nation or international organization; or 21 B. in the case of communication or exchange of information or access to materials or equipment, the originating Party has informed the recipient Party that the originating Party has so communicated or exchanged such information to, or permitted access to such materials or equipment by, such other nation or international organization; or C. in the case of material which has lost its identity as a result of commingling with other material of the recipient Party, the recipient Party retains an amount under its jurisdiction equivalent to that made available to it by the originating Party under this Agreement. ARTICLE VIII New 2024 version of Article VIII adds Information-Security Policies paragraph B, allowing for the treaty to encompass A. Agreed information-security policies shall be maintained with respect to all new information information, materials or equipment communicated, exchanged or transferred under this classification categories Agreement. The Parties intend to continue the present practice of consultation with each without needing to other on these matters. update the treaty text. Paragraph A includes B. In the event that either Party updates its national information-security terminology updated terminology. referred to in Article XI, it shall notify the other Party in writing and, upon mutual written determination, the relevant definition(s) shall be read using the updated terminology for the purposes of this Agreement. ARTICLE IX Updated 2024 version of Article IX contains Intellectual Property similar provisions to the previous text, A. The Parties shall ensure adequate and effective protection of intellectual property using updated and created or furnished under this Agreement and relevant implementing instruments. expanded terminology, Rights to such intellectual property shall be allocated as provided in this Article. commensurate with other 2024 changes. New B. With respect to any invention or discovery employing or derived from information, paragraphs A, E and F material or equipment which has been communicated, exchanged or transferred (3) set out some general pursuant to this Agreement and made or conceived by the recipient Party, or any agency principles, provision or corporation owned or controlled thereby, or any of their agents or contractors, or any for implementing employee of any of the foregoing, after the date of such communication, exchange or agreements, and rules transfer but during the period of this Agreement: about publishing 1. i n the case of any such invention or discovery in which rights are owned by the information. recipient Party, or any agency or corporation owned or controlled thereby, and not included in subparagraph 2 of this paragraph, the recipient Party shall, to the extent owned by any of them: (a) t ransfer and assign to the originating Party all right, title and interest in and to the invention or discovery, including any patent application or patent thereon, in the country of the originating Party, subject to the retention of a royalty- free, non-exclusive, irrevocable license for the governmental purposes of the recipient Party and for the purposes of mutual defense; and (b) g rant to the originating Party a royalty-free, non-exclusive, irrevocable license for the governmental purposes of the originating Party and for purposes of mutual defense worldwide, including use in the production of material for sale to the recipient Party by a contractor of the originating Party; 22 2. i n the case of any such invention or discovery which is primarily useful in the production or utilization of special nuclear material or atomic energy and made or conceived prior to the time that the information it employs is made available for civil uses, the recipient Party shall: (a) obtain, by appropriate means, sufficient right, title and interest in and to the invention or discovery, including any patent application or patent thereon, as may be necessary to fulfill its obligations under the following two subparagraphs; (b) t ransfer and assign to the originating Party all right, title and interest in and to the invention or discovery, including any patent application or patent thereon, in the country of the originating Party, subject to the retention of a royalty- free, non-exclusive, irrevocable license, with the right to grant sublicenses, for all purposes; and (c) g rant to the originating Party a royalty-free, non-exclusive, irrevocable license, with the right to grant sublicenses, for all purposes worldwide. C. 1. E ach Party shall, to the extent owned by it, or any agency or corporation owned or controlled thereby, grant to the other Party a royalty-free, non-exclusive, irrevocable license to manufacture and use the subject matter covered by any patent and incorporated in any material or equipment transferred pursuant to this Agreement for use by the licensed Party for the purposes set forth in paragraph C of Article V. 2. T he originating Party neither warrants nor represents that any information, material or equipment transferred under this Agreement does not infringe any patent owned or controlled by other persons and assumes no liability or obligation with respect thereto, and the recipient Party waives all of its claims against the originating Party and its employees, for any and all liability arising out of any infringement of any such patent. D. With respect to any invention or discovery, including any patent application or patent thereon, or license or sublicense therein, covered by paragraph B of this Article, each Party: 1. m ay, to the extent of its right, title and interest therein, deal with the same worldwide (other than in the country of the other Party) as it may desire, but shall in no event discriminate against citizens of the other Party in respect of granting any license or sublicense under the patents owned by it worldwide; and 2. h ereby waives all of its claims against the other Party for compensation, royalty or award. E. The Parties may conclude an implementing agreement or agreements for the purpose of allocating intellectual property rights arising under this Agreement other than those allocated in paragraphs B through D of this Article. Any implementing agreement shall be consistent with this Agreement. 23 F. Notwithstanding anything to the contrary in this Article or in any implementing agreement concluded pursuant to paragraph E of this Article: 1. N o patent application with respect to any invention or discovery employing or derived from information, material or equipment communicated, exchanged or transferred pursuant to this Agreement that includes Classified Information, Controlled Unclassified Information, technical data or technology subject to either Party’s export control requirements, Sensitive Nuclear Technology, or Controlled Nuclear Information, may be filed: (a) b y either Party or any person in the country of the other Party except in accordance with agreed conditions and procedures; or (b) i n any jurisdiction not of a party to this Agreement except as may be agreed and subject to Articles VI and VII. 2. A ppropriate secrecy or prohibition orders shall be issued for the purpose of giving effect to paragraph F(1) of this Article. 3. A ny intended publication of information employing or derived from information communicated or exchanged under the Agreement or related to material or equipment transferred under this Agreement shall be subject to both Parties’ respective review processes for: Classified Information, Controlled Unclassified Information, technical data or technology subject to export control requirements, Sensitive Nuclear Technology, and Controlled Nuclear Information. Classified Information, Controlled Unclassified Information, technical data or technology subject to export control requirements, or Controlled Nuclear Information communicated or exchanged pursuant to this Agreement, or derived from information so communicated or exchanged, may not be published except in accordance with both Parties’ applicable laws and regulations and only following such review by the Parties. ARTICLE X Previous Agreements for Cooperation Effective from the date on which the present Agreement enters into force, the cooperation between the Parties being carried out under or envisaged by the Agreement for Cooperation Regarding Atomic Information for Mutual Defence Purposes, which was signed at Washington on June 15, 1955,I and by paragraph B of Article I bis of the Agreement for Cooperation on Civil Uses of Atomic Energy, which was signed at Washington on June 15, 1955,II as amended by the Amendment signed at Washington on June 13, 1956,III shall be carried out in accordance with the provisions of the present Agreement. I. United Nations, Treaty Series, Vol. 214, p. 301. II. United Nations, Treaty Series, Vol. 229, p. 73. III. United Nations, Treaty Series, Vol. 252, p. 394. 24 ARTICLE XI Definitions For the purposes of this Agreement: A. ‘Atomic weapon’ means any device utilizing atomic energy. exclusive of the means for transporting or propelling the device (where such means is a separable and divisible part of the device), the principal purpose of which is for use as, or for development of, a weapon, a weapon prototype, or a weapon test device. B. “Classified Information” means information, data, materials, services or any other 2024 version of matter within the scope of this Agreement with the security designation of United States paragraph uses “Confidential” or higher or, with respect to the United Kingdom, a security designation updated information of “OFFICIAL-SENSITIVE” or higher, as applied under the laws or regulations of classification categories. either the United States or the United Kingdom, respectively. “Classified Information” A reference to additional includes Atomic Information and that designated by the United States as National UK categories had been Security Information. added in 2014. C. “Controlled Unclassified Information” means information created or possessed Definitions of sensitive by either Party that requires safeguarding or dissemination controls pursuant to and nuclear technology and consistent with applicable law, regulations and government-wide policies but is not controlled information Classified Information. For the United States, this means information designated as added in 1984. (U.S.) Controlled Unclassified Information. D. “Sensitive Nuclear Technology” means any information (including information incorporated in a production or utilization facility or important component part thereof) which is not available to the public and which is important to the design, construction, fabrication, operation or maintenance of a uranium enrichment or nuclear fuel reprocessing facility or a facility for the production of heavy water, but shall not include Classified Information. E. “Controlled Nuclear Information” means unclassified information protected by the Government of the United States from unauthorized dissemination pursuant to sections 57.b. or 148 of the United States Atomic Energy Act of 1954, as amended. F. “Equipment” means any instrument, apparatus or facility and includes any facility, except an atomic weapon, capable of making use of or producing special nuclear material, and component parts thereof, and includes naval nuclear propulsion plants or parts thereof, reactors, and military reactors. “Equipment” also includes non-nuclear Definition of ‘equipment’ parts of atomic weapons and other non-nuclear parts of atomic weapons systems enlarged to include involving Restricted Data. non-nuclear weapon components in 1959. G. ‘Military reactor’ means a reactor for the propulsion of naval vessels, aircraft or land vehicles and military package power reactors. H. ‘Person’ means: 1. any individual, corporation, partnership, firm, association, trust, estate, public or Agency names removed private institution, group, government agency or government corporation other in 1979 and replaced than the United Kingdom Ministry of Defence and the United States Department with government of Energy and departments. 2. a ny legal successor, representative, agent or agency of the foregoing 25 I. “Reactor” means an apparatus, other than an atomic weapon, in which a self- supporting fission chain reaction is maintained and controlled by utilizing uranium, plutonium or thorium, or any combination of uranium, plutonium or thorium. Paragraph referring to the UKAEA deleted in 1974. J. “Naval nuclear propulsion plant” means a propulsion plant and includes the reactor, Amended in 2024 for and such control, primary, auxiliary, steam and electric systems as may be necessary for treaty to allow for propulsion of naval vessels. transfer of any type of naval reactor under K. “Non-nuclear parts of atomic weapons” means parts of atomic weapons which are the treaty, not just specially designed for them and are not in general use in other end products and which submarines. are not made, in whole or in part, of special nuclear material; and “other non-nuclear parts of atomic weapons systems involving Restricted Data” means parts of atomic Definitions of non- weapons systems, other than non-nuclear parts of atomic weapons, which contain or nuclear parts and atomic reveal Atomic Information and which are not made, in whole or in part, of special information added in nuclear material. 1959. L. “Atomic Information” means information designated as Restricted Data or Formerly Amended in 2024 for Restricted Data by the United States and information designated as ATOMIC by the stylistic consistency. United Kingdom. M. “Nuclear security enterprise” means, for the United States, the physical infrastructure, New definitions added technology and workforce at the national security laboratories and atomic weapons in 2024. production sites, as well as the Nevada National Security Site and the National Nuclear Security Administration’s Office of Secure Transportation, and for the United Kingdom, the equivalent physical infrastructure, technology and workforce associated with the defence nuclear enterprise. N. “Naval Nuclear Propulsion Information” or “NNPI” means information concerning the design, arrangement, development, manufacture, testing, operation, administration, training, maintenance or repair of the naval nuclear propulsion plants of naval nuclear- powered vessels and prototypes, including the associated shipboard and shore-based nuclear support facilities, and consists of Classified Information and Controlled Unclassified Information. O. “National Security Information” means information that has been determined pursuant to U.S. Executive Order No. 13526 or any predecessor or successor order to require protection against unauthorised disclosure and is marked to indicate its classified status when in documentary form. P. “Originating Party” means the Party that originally communicates, exchanges or transfers information, material or equipment, as applicable. Q. “Recipient Party” means the Party that originally receives the communication, exchange or transfer of information, material or equipment, as applicable. 26 ARTICLE XII Final Provisions In 2024 the article on duration was renamed. A. This Agreement shall enter into force on the date on which each Government shall have received from the other Government written notification that it has complied with Some more complex all statutory and constitutional requirements for the entry into force of this Agreement, wording on terminating and shall remain in force until terminated by agreement of both Parties, except that, the agreement was if not so terminated, Article II may be terminated by agreement of both Parties, or by removed in 1984. either Party on one year’s notice to the other to take effect on December 31, 1969, or thereafter on one year’s notice to take effect at the end of any succeeding term of five In 1959 a specific date years. was given for the earliest termination of Article II B. Following termination of this Agreement, information, material or equipment sharing. communicated, exchanged or transferred pursuant to this Agreement prior to the effective date of termination shall continue to be treated in accordance with Articles Paragaphs added in 2024 IV, V(C), VI(A, B, C, D, F and G), VII, VIII and IX. Additionally, termination of this to specify that some Agreement shall not affect rights or obligations under Article IX. conditions persist after the end of the agreement, C. The Parties may enter into implementing instruments to implement the provisions of prevent external dispute the Agreement. In case of any inconsistency between an implementing instrument and settlement mechanisms this Agreement, this Agreement shall prevail. being used, and allow for implementing D. The Parties shall settle any disagreements arising in the implementation or instruments. interpretation of this Agreement through mutual consultations without recourse to any dispute settlement mechanisms. 27 Endnotes 1. ‘US-UK Mutual Defence Agreement’. 8. ‘Amendment to the Agreement between the Government Hansard Vol. 587 Col. 312WH, 6 November of the United Kingdom of Great Britain and Northern 2014. https://hansard.parliament.uk/ Ireland and the Government of the United States Commons/2014-11-06/debates/14110640000001/US- of America for Cooperation on the Uses of Atomic UKMutualDefenceAgreement. Energy for Mutual Defense Purposes’, 22 July 2014. Her 2. Unless otherwise stated this section is based on Jenifer Majesty’s Stationery Office. Cm 8996. https://treaties. Mackby and John Simpson. ‘The Special Nuclear fcdo.gov.uk/awweb/awarchive?type=file&item=70116. Relationship: A Historical Chronology’. In US-UK Nuclear 9. ‘Amendment to the Agreement between the Government Cooperation after 50 Years, edited by Jenifer Mackby, and of the United Kingdom of Great Britain and Northern Paul Cornish. Washington, DC: Center for Strategic and Ireland and the Government of the United States of International Studies, 2008. p5–12. America for Cooperation on the Uses of Atomic Energy 3. Richard Moore. ‘British Nuclear Warhead Design for Mutual Defense Purposes’. Her Majesty’s Stationery 1958–66: How Much American Help?’ Defence Studies 4, Office, 23 May 1994. Cm 2785. https://treaties.fcdo.gov.uk/ no. 2 (January 2004): 207–28. https://doi.org/10.1080/1470 data/Library2/pdf/1995-TS0022.pdf. 243042000325913. 10. ‘Amendment to the Agreement’, 2014. Op. Cit. 4. For example: AWE. ‘Legacy’. https://www.awe.co.uk/ 11. Mackby and Simpson, 2008. Op. Cit. p11. about-us/our-history/. 12. Ibid. p14–15. 5. As of 2014, stocktake meetings were held approximately 13. See David Cullen. ‘Extreme Circumstances: The every 18 months. See: Claire Mills. ‘UK-US Mutual UK’s New Nuclear Warhead in Context.’ Nuclear Defence Agreement’. Standard Note. House of Commons, Information Service, August 2022. p28–30; 34–37. https:// 20 October 2014. SN/IA/3147. https://researchbriefings. www. nuclearinfo.org/wp-content/uploads/2022/08/ files.parliament.uk/documents/SN03147/SN03147.pdf ExtremeCircumstances-print-version.pdf. 6. ‘Amendment to the Agreement between the 14. ‘Operation DOMINIC I – Fact Sheet’. Defense Threat Government of the United Kingdom of Great Britain Reduction Agency, September 2021. https://www. and Northern Ireland and the Government of the dtra.mil/Portals/125/Documents/NTPR/newDocs/18- United States of America for Co-Operation on the DOMINIC%20I%20-%202021.pdf. Uses of Atomic Energy for Mutual Defense Purposes 15. Ian Zabarte. ‘A Message from the Most Bombed Nation of July 3, 1958’. Her Majesty’s Stationery Office, 25 on Earth’. Al Jazeera. Accessed 11 July 2024. https://www. July 2024. https://assets.publishing.service.gov.uk/ aljazeera.com/opinions/2020/8/29/a-message-from-the- media/66a35cd9fc8e12ac3edb051f/CS_USA_1.2024_UK_ most-bombed-nation-on-earth. USA_Amendment_Agreement_Atomic_Energy_Mutual_ 16. ‘The Republic of Kiribati’s Submission in Accordance Defense_Purposes.pdf. With Resolution 78/240 Entitled Addressing the 7. ‘Amendment to the Agreement between the Government Legacy of Nuclear Weapons’. Republic of Kiribati, 31 of the United Kingdom of Great Britain and Northern May 2024. https://docs-library.unoda.org/General_ Ireland and the Government of the United States of Assembly_First_Committee_-Seventy-Ninth_session_ America for Cooperation on the Uses of Atomic Energy (2024)/78-240-Kiribati-EN_0.pdf. for Mutual Defense Purposes’. Her Majesty’s Stationery 17. John Lax and Ceri McDade. ‘Buckets of Sunshine in a Office, February 1985. Cmnd. 9434. https://treaties.fcdo. Broken Paradise – the Operation Dominic Nuclear Test gov.uk/data/Library2/pdf/1985-TS0004.pdf. Series, 1962, Christmas Island.’ The British Nuclear Test Veterans Association, 25 April 2021. https://www.bntva. com/buckets-of-sunshine-in-a-broken-paradise-the- operation-dominic-nuclear-test-series-1962-christmas- island. 18. See Cullen, 2022. Op. Cit. p12–13. 28 19. Sanem Topal. ‘Nuclear Weapon Modernisation: Attitudes 33. Rabinder Singh and Christine Chinkin. ‘Peacerights, of Non-Nuclear Weapon States’. Nuclear Information BASIC and the Acronym Institute for Disarmament Service, August 2021. https://www.nuclearinfo.org/wp- Diplomacy: Mutual Defence Agreement and the Nuclear content/uploads/2021/08/Attitudes-to-Nuclear-Weapons- Non-Proliferation Treaty Joint Advice’. Matrix, 20 Modernisation.pdf. July 2004. https://www.nuclearinfo.org/wp-content/ 20. ‘Plutonium and Aldermaston – an Historical Account’. uploads/2020/09/Mutual-Defence-Agreement-and-the- Ministry of Defence, 2000. Nuclear-Non-Proliferation-Treaty-Joint-Advice.pdf. 21. Ibid. 34. ‘US-UK Mutual Defence Agreement’. 22. Bob Ainsworth. ‘Trident Missiles: 3 Dec 2009’. Hansard Hansard, Vol. 587 Col. 313WH, 6 November Column 909W, 3 December 2009. https://publications. 2014. https://hansard.parliament.uk/ parliament.uk/pa/cm200910/cmhansrd/cm091203/ Commons/2014-11-06/debates/14110640000001/US- text/91203w0014.htm#09120373000544. UKMutualDefenceAgreement. 23. ‘Defence Board – Successor Submarine Project – Note 35. For a detailed discussion of this increase, see: Cullen, by the Assistant Secretary’, 25 November 2009. https:// 2022. Op. Cit. p15. robedwards.typepad.com/files/declassified-report-to- 36. ‘Amendment to the Agreement between the mod-defence-board.pdf. Government of the United Kingdom of Great Britain 24. Ministry of Defence. ‘FOI2024/04354 – MDA Transfers – and Northern Ireland and the Government of the Response’, 11 April 2024. United States of America for Co-Operation on the 25. Ministry of Defence. ‘FOI2024/06131 – Steve Uses of Atomic Energy for Mutual Defense Purposes Hucklesby – MDA Joint Working Groups’, 4 June of July 3, 1958’. Her Majesty’s Stationery Office, 25 2024. https://www.whatdotheyknow.com/request/ July 2024. https://assets.publishing.service.gov.uk/ active_joint_working_groups_jowo?nocache=incoming- media/66a35cd9fc8e12ac3edb051f/CS_USA_1.2024_UK_ 2672234#incoming-2672234. USA_Amendment_Agreement_Atomic_Energy_Mutual_ 26. Moore, 2004. Op. Cit. Defense_Purposes.pdf. 27. Ministry of Defence, 2024. Op. Cit. 37. Claire Mills. ‘Amendments to the UK-US Mutual Defence 28. Ibid. Agreement’. House of Commons Library, 2 September 29. ‘Reform, Not Renewal – The US-UK Mutual Defence 2024. Number 10086. https://researchbriefings.files. Agreement, How It Works and Why It Needs to Be parliament.uk/documents/CBP-10086/CBP-10086.pdf. Reformed’. Nuclear Information Service, 2014. https:// 38. ‘Amendment to the Agreement Between the United www.nuclearinfo.org/wp-content/uploads/2022/07/ States of America and the Government of the United Reform-Not-Renewal-Full-Report.pdf. Kingdom of Great Britain and Northern Ireland for 30. ‘Nuclear Weapons’. Hansard, 20 January 2011. Cooperation on the Uses of Atomic Energy for Mutual Column 881W. https://publications.parliament.uk/ Defense Purposes of July 3, 1958’. U.S. Government pa/cm201011/cmhansrd/cm110120/text/110120w0001. Publishing Office, 30 July 2024. https://www.govinfo.gov/ htm#11012056001705. content/pkg/CDOC-118hdoc156/pdf/CDOC-118hdoc156. 31. Atomic Weapons Establishment. ‘FOI2024-033 -Final pdf Response’, 18 June 2024. 39. Ryan Zinke. ‘Text - H.R.9718 - 118th Congress (2023-2024): 32. Stuart Andrew. ‘USA: Trident Submarines – Question Extending and Enhancing U.S.-U.K. Nuclear Cooperation for Ministry of Defence – Written Questions, Answers’. for Mutual Defense Purposes Act’. Legislation, 24 Hansard, 19 October 2018. https://questions-statements. September 2024. 2024-09-20. https://www.congress.gov/ parliament.uk/written-questions/detail/2018-10-19/181551. bill/118th-congress/house-bill/9718/text/ih. 29 40. Information taken from: ‘FOI2024/06131’, 2024. Op. 41. Text compiled by Nuclear Information Service. All Cit.; ‘Mutual Defence Agreement’. Hansard Vol. 412, effort has been made to ensure accuracy. Sources: 3 November 2003. https://hansard.parliament.uk/ ‘Agreement between the Government of the United Commons/2003-11-03/debates/10e95018-9e3c-4621- Kingdom of Great Britain and Northern Ireland and aa7a-355ef4fbefb2/MutualDefenceAgreement; ‘Nuclear the Government of the United States of America for Weapons’. Hansard Vol. 408, 11 July 2003. https://hansard. Co-Operation on the Uses of Atomic Energy for Mutual parliament.uk/Commons/2003-07-11/debates/6276acf0- Defense Purposes.’ UN, 3 July 1958. Cmnd 537. https:// 88ab-45b2-b26d-e3d3db28d912/NuclearWeapons; ‘Joint treaties.fcdo.gov.uk/data/Library2/pdf/1958-TS0041. Working Groups’. Hansard Vol. 304, 12 January 1998. pdf; ‘Amendment to the Agreement between the https://hansard.parliament.uk/Commons/1998-01-12/ Government of the United Kingdom of Great Britain debates/0c7e8f58-693e-414c-aee2-0a6e831128ae/ and Northern Ireland and the Government of the JointWorkingGroups; ‘Mutual Defence Agreement’. United States of America for Co-Operation on the Uses Hansard Vol. 289, 27 January 1997. https://hansard. of Atomic Energy for Mutual Defense Purposes of July parliament.uk/Commons/1997-01-27/debates/095ae56f- 3, 1958’. Her Majesty’s Stationery Office, 7 May 1959. e616-49ec-931f-201fcea72681/MutualDefenceAgreement; Cmnd. 859. https://treaties.fcdo.gov.uk/data/Library2/ ‘Agreement’. Hansard Vol. 254 Col. 823, 16 February 1995. pdf/1980-TS0061.pdf; ‘Amendment to the Agreement https://hansard.parliament.uk/Commons/1995-02-16/ between the Government of the United Kingdom of debates/ffa95c2f-1d58-430e-b8d0-309823f8dc6a/ Great Britain and Northern Ireland and the Government Agreement; ‘Joint Working Groups’. Hansard Vol. of the United States of America for Co-Operation on the 378 Col. 1116W, 25 January 2002. https://hansard. Uses of Atomic Energy for Mutual Defense Purposes parliament.uk/Commons/2002-01-25/debates/fdaef039- of July 3, 1958’. Her Majesty’s Stationery Office, 27 618c-4383-b4f8-c0975ec9fb35/JointWorkingGroups; September 1968. Cmnd. 4119. https://treaties.fcdo.gov.uk/ ‘Nuclear Weapons’. Hansard Vol. 488, 27 February 2009. awweb/awarchive?type=file&item=66769; ‘Amendment https://hansard.parliament.uk/commons/2009-02-27/ to the Agreement between the Government of the debates/09022737000121/NuclearWeapons. The full title United Kingdom of Great Britain and Northern Ireland of JOWOG 11 is ‘Analysis and specification of materials and the Government of the United States of America to arrive at common standards’. This figure is based on for Co-Operation on the Uses of Atomic Energy for the assumption that JOWOGs are in general active on Mutual Defense Purposes of July 3, 1958’. Her Majesty’s an ongoing basis until their work is no longer deemed Stationery Office, 22 July 1974. Cmnd. 6017. https:// necessary, whereas actual activity patterns may be treaties.fcdo.gov.uk/awweb/pdfopener?md=1&did=67364; more complex. The numbering of JOWOGs 16-21 can be ‘Amendment to the Agreement between the Government inferred, but is not certain. The year that some JOWOGs of the United Kingdom of Great Britain and Northern became active between 1973 and the status of some Ireland and the Government of the United States JOWOGs in 2024 is not certain and is indicated by partial of America for Cooperation on the Uses of Atomic shading in those years. Some JOWOGs shown as active Energy for Mutual Defense Purposes of July 3, 1958’. in 1995 have not been confirmed as separate groups Her Majesty’s Stationery Office, 5 December 1979. as data in that year is described as ‘subject areas’. The Cmnd. 7976. https://treaties.fcdo.gov.uk/data/Library2/ number of the JOWOG focussing on ‘Weapons Material pdf/1980TS0061.pdf; ‘Amendment to the Agreement’, Management’ and the title of JOWOG 47 cannot be 1985. Op. Cit.; ‘Amendment to the Agreement’, 1994. determined from the available data. Op. Cit.; ‘Amendment to the Agreement’, 2014. Op. Cit.; ‘Amendment to the Agreement’, 2024. Op. Cit. 30 Nuclear Information Service This briefing and a full list of our reports and briefings Reports and briefings are provided free of charge but is available at www.nuclearinfo.org/reports please consider making a donation to support our work. Printed copies can be ordered. Donate: www.nuclearinfo.org/donate Stay in touch: www.nuclearinfo.org Recent publications Facebook: www.facebook.com/Nuclearinfo YouTube: www.youtube.com/nuclearinfo Devonport: A Nuclear Information Service Twitter/X: @Nuclearinfo Briefing An overview of the Devonport Royal Dockyard and its role in servicing the UK’s nuclear submarine fleet. isBn 978-1-9993413-4-3 Extreme Circumstances: The UK’s new nuclear This work is licensed under a Creative Commons warhead in context Attribution-NonCommercial-NoDerivatives 4.0 Detailed information from UK and US sources on the International License (CC BY-NC-ND 4.0), except images replacement nuclear warhead programme. where noted. 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