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The DPRK has exceptionally mentioned the yield range of the reported hydrogen bomb at the sixth nuclear test in 2017. The Korean Central News Agency reported that “our hydrogen bomb, the explosive power of which is adjustable from tens of kilotons to hundreds of kilotons... [핵탄위력을 타격대상에 따라 수십kt급으로부터 수백kt급에 이르기까지 임의로 조정할 수 있는 우리의 수소탄은…]” and highlighted that the test demonstrated not only the “enormous destructive power [거대한 살상파괴력]” of the hydrogen bomb, but also its “strategic purpose to deliver a super-powerful EMP attack over a vast area [광대한 지역에 대한 초강력 EMP 공격].”(a) Moreover, the report emphasized a “Juche-oriented thermonuclear weapon [주체식 열핵무기]” that is “based on our own effort and technology [우리의 힘과 기술].” (a)
The Ministry of Foreign Affairs of the DPRK highlighted that the success of the nuclear test “demonstrates that not only have our own nuclear bombs become highly precise, but the operational reliability of their nuclear warheads is firmly guaranteed; our nuclear weapons design and manufacturing technology has reached a high level that allows the power of nuclear bombs to be adjusted arbitrarily depending on the target and purpose of the strike. It is a very significant milestone in achieving the final-stage goal of completing the national nuclear force. [우리의 주체적인 핵탄들이 고도로 정밀화되였을뿐아니라 핵전투부의 동작믿음성이 확고히 보장되며 우리의 핵무기설계 및 제작기술이 핵탄의 위력을 타격대상과 목적에 따라 임의로 조정할수 있는 높은 수준에 도달하였다는것을 명백히 보여주었으며 국가핵무력완성의 완결단계목표를 달성하는데서 매우 의의있는 계기로 된다]”.(b)
Such statements emphasized self-reliance in nuclear weapons development, the reliability of the weapon system, and the strategic significance of the hydrogen bomb for the DPRK.
France does not currently reveal any information on the yield of its two types of nuclear warheads, the Oceanic Nuclear Warhead (TNO) used on submarine-launched ballistic missiles and the Airborne Nuclear Warhead (TNA) used on airborne cruise missiles. President Mitterrand declared in 1994 that a warhead used for then-used submarine-launched submarines had a yield of 150 kilotonnes, and that the warheads deployed on then-used cruise missiles was 300 kilotonnes 1. No information has been published ever since at the official level on the issue of yield, and information reported by the media is never backed by credible assessments. The manufacturer of the cruise missiles that carries the TNA only indicated on its website that its yield is “medium energy” 2.
Pakistan has never disclosed the yields of its warheads and has provided no information regarding its nuclear arsenal. There are speculations about the yields of its nuclear weapon tests conducted in 1998 but these were also never confirmed by the government.
The explosive yields of UK warheads are classified 1. However, the UK Holbrook warhead is understood to have a yield of 80-100 kilotons 2. The House of Commons Library stated in a report in 2016 that the UK warhead “is believed to be closely related to the American W76 warhead, a thermonuclear warhead in the 80-100 kiloton range”.(3)
This is because the UK Holbrook warhead is understood to be an Anglicised version of the US W76-1 warhead. For example, Franklin Miller KGB, Special Advisor to President George W Bush and Senior Director for Defense Policy and Arms Control, described the UK warhead as “their W76 variant”. (4) The W76 warhead is widely understood to have an explosive yield of 80-100 kt. However, this figure has not been declared in official US documents.
This is because the US deploys the W76-1 warhead on its Trident II (D5) SLBMs. The UK also deploys its Holbrook warhead on Trident II (D5) SLBMs under a lease arrangement for 58 missile bodies drawn from a common pool in the US (5). The UK warhead therefore has to match the size, mass, centre of gravity and other characteristic requirements for the US-supplied warhead re-entry body designed to operate with Trident missile.
The Holbrook warhead can also be detonated at a lower yield, described in the 1990s as a ‘sub-strategic’ option (6) by configuring a warhead to detonate the primary stage only and/or adjusting the height of the detonation over the target (7). The government confirmed in 1997 that “The UK has some flexibility in the choice of yield for the warheads on its Trident missiles” (8). The US deployed a reduced yield variant of its W76 warhead (the W76-2 in 2019 by configuring a small number of existing warheads for primary-only detonation (9).
The United States does not disclose the exact yields of the warheads in its current arsenal. However, it does occasionally disclose information about current warheads that would help analysts make educated assumptions about their yields, particularly by disclosing information about warhead designs or yields relative to other weapons. For example, in its announcement describing the development of the new B61-13 gravity bomb, the Department of Defense stated that the weapon would "have a yield similar to the B61-7, which is higher than that of the B61-12." 1
The United States has also declassified the exact yields of many of its nuclear tests, as well as the yields of some nuclear weapons that are no longer in the US arsenal. [2, 3, 4] For example, the yield of the B53––once the highest-yield nuclear weapon in the US arsenal––was officially declassified in 2014 and revealed to be 9 megatons, although it had already been retired and dismantled by that time. 5 In addition, the United States has declassified the total megatonnage in its arsenal between 1945 (0.04 megatons) and 1994 (2,375.3 megatons); the year of the largest stockpile megatonnage was 1960 (20,491.17 megatons). 6 While this dataset was not disaggregated by weapon, it can be used to make analytical estimates for individual warheads.
While no official records have been released by the DPRK government, expert estimates are primarily based on or start with the plutonium production capacity of the 5 MWe reactor.[2,3,4,5] This reactor is believed to be capable of producing 6 kg of plutonium per year.1 Depending on the designs and sophistication of its nuclear weapons program, a nuclear bomb could require as little as 3.5 kg of plutonium.6 The existence of this reactor was acknowledged in the Agreed Framework signed between the DPRK and the USA in 1994.(a) Experts have estimated that the DPRK might have produced sufficient fissile material to potentially build up to 90 nuclear weapons but assembled around 50.6 However, the DPRK government has never acknowledged this estimation.
France reveals that it is holding less than 300 nuclear weapons. President François Mitterrand gave precise numbers on the French stockpile for the first time in his speech of 1994, numbering almost 500 weapons 1. In 2008, President Sarkozy mentioned the reductions in the stockpile operated since the end of the Cold War and indicated that the French arsenal would from then on be composed of less than 300 nuclear warheads 2. President Hollande and Macron repeated this information respectively in 2015 3 and 2020 4. The approximate data is also available in France's NPT transparency reports 5.
The Government of Pakistan as a matter of policy does not declare the number of warheads in its inventory. Pakistan maintains ambiguity about its nuclear weapons program and has never disclosed the capacity of its nuclear facilities for producing fissile material stocks. A plausible reason for maintaining this ambiguity is that it doesn't want to engage in an arms race with its main rival India, which Pakistan believes has more production capacity for fissile material production and the warheads. Competing with India in numbers game, according to Pakistan would unnecessarily burden its limited resources.
The UK government does not disclose the total number of nuclear warheads in its stockpile. Instead, it has regularly disclosed a warhead ceiling. The most recent disclosure was in Conservative Johnson government’s 2021 Integrated Review of Security, Defence, Development and Foreign Policy. This stated that the government was increasing the overall nuclear weapon stockpile to no more than 260 warheads 1. The most recent Strategic Defence Review and National Security Strategy published by the Labour Starmer government in 2025 did not declare a warhead ceiling (2).
The announcement in 2021 signalled the end of a post-Cold War series of reductions in the overall nuclear weapon stockpile as follows:
- In 1988 Conservative Thatcher government announced its intention to limit the total number of warheads for the new Trident system to 512 and that it would deploy no more than 128 warheads per submarine (3).
- This was reduced again in 1995 to a total of 300 warheads a maximum of 96 per submarine and later to a maximum of 60 warheads per submarine (4).
- In 1998 the Labour Blair government announced a reduction in the number of operationally available Trident warheads to no more than 200 (5).
- In 2006 the Labour government announced that it would reduce the number of operationally available warheads by 20% to 160 (6).
- In 2010 the Conservative-Liberal Democrat Coalition government’s announced its intention to reduce its overall nuclear warhead stockpile ceiling from not more than 225 to not more than 180 by the mid 2020s and reduce its operationally available warheads from fewer than 160 to no more than 120 in its 2010 Strategic Defence and Security Review. (7).
- In 2015 the 2010 statement was repeated in the Conservative Cameron government’s Strategic Defence and Security Review. (8)
The United States is the only country to periodically disclose the size of its current nuclear stockpile, the number of annually dismantled warheads, and the approximate number of retired warheads awaiting dismantlement. It did this for the first time in 2010, when the Obama administration declassified the entire history of the US nuclear stockpile, including the annual stockpile size, the number of dismantled warheads since 1994, and the number of retired warheads awaiting dismantlement. 4 The United States continued to disclose these data on an annual basis until 2019, when the US Department of Defense denied successive declassification requests until 2021, when transparency was restored and the figures from the missing years were disclosed. [5, 6] Another disclosure of these figures was made in 2024, similarly restoring the previous years' missing data. 1 It appears that the United States is shifting towards disclosing these figures on an ad hoc, rather than annual, basis.
In addition, as a party to New START––a bilateral treaty between the United States and Russia limiting numbers of deployed strategic warheads and launchers––the United States released its aggregate numbers of strategic warheads on deployed intercontinental ballistic missiles, submarine-launched ballistic missiles, and nuclear warheads counted for deployed heavy bombers on a biannual basis throughout most of the duration of the treaty. 2 Although it did not publish the disaggregated data, this data was available upon request from the Department of State throughout this time. Following Russia's unilateral suspension of New START in February 2023, the United States disclosed one final set of deployment-related treaty data from March 2023, but subsequently has not released any deployment data since then. 3
According to its 2022 Law on Nuclear Force, three out of the five conditions when the DPRK would use its nuclear weapons included general information related to the types of weapons that might be used by an adversary.(a) The DPRK does not go into the details in terms of mentioning the specific types of strategic non-nuclear technologies but they should be included as part of non-nuclear attacks.
In specific, under the Article 6 of this law, these three conditions are: 1 조선민주주의인민공화국에 대한 핵무기 또는 기타 대량살륙무기공격이 감행되였거나 림박하였다고 판단되는 경우 [if a nuclear weapon or other weapons of mass destruction attack against the DPRK is assessed to have been carried out or is imminent]; 2 국가지도부와 국가핵무력지휘기구에 대한 적대세력의 핵 및 비핵공격이 감행되였거나 림박하였다고 판단되는 경우 [if a nuclear or non-nuclear attack by hostile forces against the state leadership and the nuclear force command organization of the state is assessed to have been carried out or is imminent]; 3 국가의 중요전략적대상들에 대한 치명적인 군사적공격이 감행되였거나 림박하였다고 판단되는 경우 [if a lethal military attack against key strategic targets of the state is assessed to have been carried out or is imminent].(a)
While France does not mention these technologies explicitly in its doctrine, the French doctrine clearly indicates that the employment of nuclear weapons in response to an attack does not depend on the type of technology used to create damages, but the level of damages and whether they put in jeopardy the vital interest of the state. This can include strikes from non-nuclear strategic weapons, but also chemical, biological attack, or large-scale conventional attacks.
Non-nuclear strategic technologies, which are not labeled as such, but may include air and missile defense as well as deep strike capacities, are mentioned in the official doctrine as capacities that may come as a support for nuclear deterrence, to increase its credibility. However, the French nuclear doctrine preserves a fundamental barrier between conventional operations and a potential use of nuclear weapons.1
Pakistan's nuclear capability is poised to deter India's conventional as well as nuclear aggression and therefore there are no clearly defined red lines. With India's development of hypersonic weapons and anti-satellite weapons, there could be a possibility that Pakistan may consider developing nuclear options, in case India uses these strategic non-nuclear capabilities to threaten Pakistan's critical infrastructure, including the nuclear capability or the associated command, control and communication infrastructure.
No. The UK does not disclose in detail how it accounts for or would respond to strategic, non-nuclear technologies (for example, cyber capabilities, anti-satellite weapons, hypersonic or precision-strike systems) in its doctrine governing the employment of nuclear weapons.
The UK does acknowledge that emerging strategic, non-nuclear technologies could influence its nuclear deterrence posture and might, in extreme circumstances, affect the conditions under which it would consider nuclear use. In 2021 the UK stated it reserved the right to review its negative security assurance in light of “emerging technologies that could have a comparable impact” to a weapon of mass destruction. It reiterated that it will remain deliberately ambiguous about precisely when, how and at what scale we would contemplate the use of nuclear weapons.1
Traditionally, each successive U.S. presidential administration issues a Nuclear Posture Review (NPR) that describes U.S. nuclear strategy, policy, posture, and forces. The policies articulated in the most recent NPR––published in 2022––were translated into an updated version of the U.S. Nuclear Employment Strategy, which was published in 2024.
The guidance included in both documents explicitly noted that the role of U.S. nuclear weapons is to deter strategic attack, which explicitly include “significant, high-consequence, non-nuclear attack[s] that ha[ve] strategic-level effect[s]” alongside nuclear attacks at any scale. [1, 2] While these terms were not defined in the 2022 NPR, they were defined in the previous 2018 NPR, as follows: Significant non-nuclear strategic attacks include, but are not limited to, attacks on the U.S., allied, or partner civilian population or infrastructure, and attacks on U.S. or allied nuclear forces, their command and control, or warning and attack assessment capabilities.” 3 The 2018 NPR also lists “chemical, biological, cyber, and large-scale conventional aggression” as examples of “non-nuclear strategic threats.” 3
The DPRK government does not issue pre-notification of its missile tests and other related activities. There are usually follow up news outlet confirming and sharing more information related the tests and exercises afterwards on the same day.(a,b,c,e,f,g)
Particularly for the fourth nuclear test and also the its first Hydrogen bomb test, the DPRK has shared a clearer timeline for issuing the order to conduct the test. Kim Jong-Un has “주체104(2015)년 12월 15일 주체조선의 첫 수소탄시험을 진행할데 대한 명령을 하달하신데 이어 주체105(2016)년 1월 3일 최종명령서에 수표하시였다. [issued an order to conduct the first H-bomb test … on December 15, Juche 104 (2015) … and then signed the final written order on January 3, Juche 105 (2016)].”(d) The fourth nuclear test occurred on the 6th of January in 2016.(e)
France has been a signatory state of the Hague Code of Conduct against the Proliferation of Ballistic Missiles (HCoC) since its adoption in 2002 and notifies its ballistic missile tests and space launches in the framework of the Code.
According to its NPT Report, between January 2015 and January 2025, France issued 97 pre-launch notifications, equal to the number of French space and ballistic missile launches conducted during that period. In fulfillment of one of the provisions of the HCoC, France hosted in 2011 an inspection by international observers at the Guiana Space Centre in Kourou (French Guiana). A second visit to Kourou was organized in December 2022. 1
Nuclear exercises conducted by the airforce are announced ahead of time via the NOTAM system and planned in a previsible manner. 2
Pakistan and India agreed to notify each other of any ballistic missile tests. This was concluded in 2005 and both countries continue to follow the practice. This agreement however doesn't include cruise missiles or space launch vehicles and the military exercises involving nuclear and dual-capable weapon systems.
The 2005 agreement has withheld despite the number of crises that both countries have experienced over the past two decades. 1
The UK participates in multilateral transparency arrangements, mainly through the Hague Code of Conduct against Ballistic Missile Proliferation (HCOC) that commits states to provide pre-launch notifications of any ballistic missile or space launch vehicle launches and annual declarations of ballistic missile and space launch policies.1 Notification is sent to the HCoC's Immediate Central Contact (ICC) managed by Austria. This includes information such as the generic class of the missile, the planned launch window, the launch area, and the planned direction that is shared with all other HCoC subscribing states through a dedicated online platform.
The UK provides post-launch notification to the UN of space launches under the 1975 Convention on Registration of Objects Launched into Outer Space. The UK also issues Notices to Airmen (NOTAM)s and marine hazard area notices for rocket launches from UK Space Agency-licensed sites.
The UK does not issue public or international pre-notifications for SSBN patrols or training related to the Trident nuclear weapon systems or joint NATO nuclear exercises such as the annual Steadfast Noon exercise. However, NATO does issue public statements on military exercise, including exercise involving nuclear assets.
The United States issues advance notice of long-range missile tests, space launch activities that might be mistaken for nuclear missile launches, and military exercises involving nuclear and dual-capable weapon systems, through three main avenues:
The United States issues notifications of launches of intercontinental ballistic missiles and submarine-launched ballistic missiles pursuant to a 1988 bilateral treaty between the United States and Russia. These notifications include the area from which the launch will take place, the geographic coordinates of the planned impact area or areas of the reentry vehicles, and must be issued no less than 24 hours in advance of launch. However, these notifications are issued through the National Nuclear Risk Reduction Centers of the two countries and are not disclosed publicly. In addition, they do not cover shorter-range missile launches. 1
The United States regularly issues press releases in advance of its long-range missile launches and nuclear weapons exercises, as these are typically planned months or years in advance and correspond to a rigorous testing schedule. For example, on November 3rd, 2025, Vandenberg Space Force Base issued a press release stating that “An operational test launch of an Air Force Global Strike Command unarmed Minuteman III intercontinental ballistic missile is scheduled between 11:01 p.m. to 5:01 a.m. Pacific Time, Nov. 4, from north Vandenberg.” 2
The United States issues regular navigational warnings to airmen and mariners for each missile and rocket test that it conducts, pursuant to the Convention on International Civil Aviation and and in support of the Global Maritime Distress and Safety System, and provides specific information about the nature of the launch, the coordinates of the launch and impact areas, and the dates under which the warning remains in effect. However, these warnings do not indicate what type of missile is being launched. 3
The DPRK has disclosed its nuclear laws twice: once in 2013 titled “자위적핵보유국의 지위를 더욱 공고히 할데 대하여 [On Consolidating the Position of Nuclear Weapons State for Self-Defence]” and in 2022, which replaced the 2013 law, titled “조선민주주의인민공화국 핵무력정책 [The DPRK’s Nuclear Force Policy].” (a,b,c)
Under Article 6 of the 2022 law, it outlines five conditions when the DPRK would use its nuclear weapons: 1 조선민주주의인민공화국에 대한 핵무기 또는 기타 대량살륙무기공격이 감행되였거나 림박하였다고 판단되는 경우 [if a nuclear weapon or other weapons of mass destruction attack against the DPRK is assessed to have been carried out or is imminent]; 2 국가지도부와 국가핵무력지휘기구에 대한 적대세력의 핵 및 비핵공격이 감행되였거나 림박하였다고 판단되는 경우 [if a nuclear or non-nuclear attack by hostile forces against the state leadership and the nuclear force command organization of the state is assessed to have been carried out or is imminent]; 3 국가의 중요전략적대상들에 대한 치명적인 군사적공격이 감행되였거나 림박하였다고 판단되는 경우 [if a lethal military attack against key strategic targets of the state is assessed to have been carried out or is imminent]; 4 유사시 전쟁의 확대와 장기화를 막고 전쟁의 주도권을 장악하기 위한 작전상필요가 불가피하게 제기되는 경우 [in the event of an contingency, if an operational necessity inevitably arises to prevent the expansion and prolongation of war and to seize the initiative in the war]; 5 기타 국가의 존립과 인민의 생명안전에 파국적인 위기를 초래하는 사태가 발생하여 핵무기로 대응할수밖에 없는 불가피한 상황이 조성되는 경우 [if any other situation arises that poses a catastrophic crisis threatens the survival of the state and the lives and safety of its people, resulting in an unavoidable situation that compels a nuclear response].(c)
In 2020, President Macron recalled the French policy regarding the employment of nuclear weapons 1. It was formalised most recently in the actualised National Strategic Review of July 2025 2: nuclear weapons are limited to "extreme circumstances of self-defence", the President is the only one in charge of determining if an attack, coming from a state, but regardless of its form (nuclear or not), endangers the vital interests of the country. If so, he may decide to employ nuclear weapons in order to inflict "absolutely unacceptable damages" upon an adversary, "a risk out of all proportion to the gains that a potential attacker could expect." The French doctrine also states that if an adversary does not perceive that it has infringed upon France's vital interests, a warning strike may be realised to reestablish deterrence. France specifies that nuclear weapons are political weapons and refuse any notion of nuclear warfighting. 3
Pakistan has not disclosed its policy regarding the employment of nuclear weapons and has maintained deliberate ambiguity about its nuclear use policy. Due to its conventional asymmetry with India, Pakistan has kept its nuclear threshold opaque and retained the option of a nuclear use. This means that it could consider the use of nuclear weapons, if its conventional military capability is considered insufficient to deal with the external threat.
The UK partially discloses its policy regarding when the employment of nuclear weapons would be considered. The UK does not set out specific conditions determining when it would consider using nuclear weapons because of the strategic importance of maintaining ‘deliberate ambiguity’. However, it does provide some parameters in terms of using nuclear weapons only in extreme circumstances of self-defence, the definition of which would be determined by the UK.
For example, the UK stated in 2021 that it “would consider using our nuclear weapons only in extreme circumstances of self-defence, including the defence of our NATO Allies” and that “While our resolve and capability to do so if necessary is beyond doubt, we will remain deliberately ambiguous about precisely when, how and at what scale we would contemplate the use of nuclear weapons”.1
The use of “extreme circumstances of self-defence” reflects wording the 1996 Advisory Opinion of the International Court of Justice on the Legality of the Use or Threat of Use of Nuclear Weapons. The ICJ concluded that it “cannot reach a definitive conclusion as to the legality or illegality of the use of nuclear weapons by a State in an extreme circumstance of self-defence, in which its very survival would be at stake”.
In 2006 the UK government stated that “In 1996 the International Court of Justice delivered an Advisory Opinion which confirmed that the use, or threat of use, of nuclear weapons is subject to the laws of armed conflict, and rejected the argument that such use would necessarily be unlawful. The threshold for the legitimate use of nuclear weapons is clearly a high one. We would only consider using nuclear weapons in self-defence (including the defence of our NATO allies), and even then only in extreme circumstances. The legality of any such use would depend upon the circumstances and the application of the general rules of international law, including those regulating the use of force and the conduct of hostilities”. 3
The UK has also eschewed language of ‘sub-strategic’ use of its Trident nuclear weapons system. It has stated that “the UK’s nuclear weapons are not designed for military use during conflict but instead to deter and prevent nuclear blackmail and acts of aggression against our vital interests that cannot be countered by other means” 4 and that “The UK does not categorise nuclear weapon capabilities as either strategic or sub-strategic/tactical. The UK and NATO have said that any employment of nuclear weapons against NATO would fundamentally alter the nature of a conflict. The UK’s nuclear weapons are a tool aiming to deter the most extreme threats to our national security and way of life, and that of our NATO Allies, rather than a warfighting capability intended to achieve a tactical or battlefield military advantage in a conflict.”5
The UK does not have a ‘no first use’ pledge. This is because “UK and NATO nuclear doctrine are consistent. NATO’s long-standing policy is neither to rule in nor rule out first use of nuclear weapons”.6 Specially: “The UK does not have a policy of no first use because—this goes to the heart of much of what we are discussing—the credibility of the deterrent rests on the conviction that we would bring all means to bear to ensure the security of the UK and our allies.”7
Traditionally, each successive U.S. presidential administration issues a Nuclear Posture Review (NPR) that describes U.S. nuclear strategy, policy, posture, and forces. The most recent iteration of the U.S. Nuclear Posture Review, issued in 2022 by the Biden administration, reaffirmed longstanding policy that the United States “maintains a very high bar for nuclear employment,” and “would only consider the use of nuclear weapons in extreme circumstances to defend the vital interests of the United States or its Allies and partners.” 1 However, the United States has traditionally not provided any specific details as to what constitute “vital interests.”
This guidance was translated into the most recent iteration of the Nuclear Employment Strategy, which was issued in November 2024 and repeats the above lines verbatim. 2
In addition, U.S. nuclear declaratory policy leaves the door open for nuclear first-use, as the most recent NPR indicated that the adoption of such a policy “would result in an unacceptable level of risk in light of the range of non-nuclear capabilities being developed and fielded by competitors that could inflict strategic-level damage to the United States and its Allies and partners.” 1 The Nuclear Employment Strategy elaborates on this further, noting that the United States “does not depend on a launch-under-attack policy to ensure a credible response.” 2
In a shift from previous guidance, the 2022 guidance requires the Department of Defense to “assess the ability of non-nuclear capabilities to contribute to deterrence, and [...] integrate these capabilities into operational plans, as appropriate.” This is being done “to advance the goal of reducing reliance on nuclear weapons [...].” 1
According to its 2022 Law on Nuclear Force, the DPRK shall not threaten to use or use nuclear weapons against non-nuclear-armed states if these states are not involved in “다른 핵무기보유국과 야합하여 조선민주주의인민공화국을 바대하는 침략이나 공격형위에 가담하지 않는한 [any aggression or attack against the DPRK in league with other nuclear-armed states].”(a)
Apart from this general provision specifically mentioning non-nuclear-armed states, under Article 6, this Law outlines five conditions under which it would use nuclear weapons, regardless of whether the state is nuclear-armed or not: 1 조선민주주의인민공화국에 대한 핵무기 또는 기타 대량살륙무기공격이 감행되였거나 림박하였다고 판단되는 경우 [if a nuclear weapon or other weapons of mass destruction attack against the DPRK is assessed to have been carried out or is imminent]; 2 국가지도부와 국가핵무력지휘기구에 대한 적대세력의 핵 및 비핵공격이 감행되였거나 림박하였다고 판단되는 경우 [if a nuclear or non-nuclear attack by hostile forces against the state leadership and the nuclear force command organization of the state is assessed to have been carried out or is imminent]; 3 국가의 중요전략적대상들에 대한 치명적인 군사적공격이 감행되였거나 림박하였다고 판단되는 경우 [if a lethal military attack against key strategic targets of the state is assessed to have been carried out or is imminent]; 4 유사시 전쟁의 확대와 장기화를 막고 전쟁의 주도권을 장악하기 위한 작전상필요가 불가피하게 제기되는 경우 [in the event of an contingency, if an operational necessity inevitably arises to prevent the expansion and prolongation of war and to seize the initiative in the war]; 5 기타 국가의 존립과 인민의 생명안전에 파국적인 위기를 초래하는 사태가 발생하여 핵무기로 대응할수밖에 없는 불가피한 상황이 조성되는 경우 [if any other situation arises that poses a catastrophic crisis threatens the survival of the state and the lives and safety of its people, resulting in an unavoidable situation that compels a nuclear response].(a)
Since 1982, France has provided negative security assurances to more than 100 non-nuclear-weapon states that comply with their non-proliferation obligations 1. This commitment by France, as well as by other nuclear-weapon states, is enshrined in Resolution 984 adopted by the United Nations Security Council (UNSC) in 1995, which was reiterated in UNSC Resolution 1887 (2009) and Resolution 2310 (2016). In 2015, the negative assurances given by France to non-nuclear-weapon states were repeated by the President of the Republic, who recognised that these were ‘legitimate’ expectations.
On 4 August 2022, the United States, France and the United Kingdom published a joint statement at the NPT Review Conference reiterating their commitment to security assurances for non-nuclear-weapon states 2.
France specifies that its negative security assurances apply to countries that are part of the Non-proliferation Treaty and comply with their non-proliferation obligations and does not affect its right of legitimate self-defence as recognised by the UN Charter 3.
Pakistan is the leading proponent for a Convention on legally binding Negative Security Assurances (NSAs). It believed that the proposal for NSA is most ripe for treaty
negotiations and has the significant potential to create the necessary environment for
confidence building and easing of tensions. 1
The UK reiterated in 2021 that “The UK will not use, or threaten to use, nuclear weapons against any non-nuclear weapon state party to the Treaty on the Non-Proliferation of Nuclear Weapons 1968 (NPT). This assurance does not apply to any state in material breach of those non-proliferation obligations. However, we reserve the right to review this assurance if the future threat of weapons of mass destruction, such as chemical and biological capabilities, or emerging technologies that could have a comparable impact, makes it necessary.”1
In 2015 the UK stated that “The UK will not use, or threaten to use, nuclear weapons against any Non-Nuclear Weapons State party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). This assurance does not apply to any state in material breach of those non-proliferation obligations. While there is currently no direct threat to the UK or its vital interests from states developing weapons of mass destruction, such as chemical and biological capabilities, we reserve the right to review this assurance if the future threat, development or proliferation of these weapons make it necessary.”2
In 2010 the UK stated that “We are now able to give an assurance that the UK will not use or threaten to use nuclear weapons against non-nuclear weapon states parties to the NPT. In giving this assurance, we emphasise the need for universal adherence to and compliance with the NPT, and note that this assurance would not apply to any state in material breach of those non-proliferation obligations. We also note that while there is currently no direct threat to the UK or its vital interests from states developing capabilities in other weapons of mass destruction, for example chemical and biological, we reserve the right to review this assurance if the future threat, development and proliferation of these weapons make it necessary”. 3
Traditionally, each successive U.S. presidential administration issues a Nuclear Posture Review (NPR) that describes U.S. nuclear strategy, policy, posture, and forces. The most recent iteration of the U.S. Nuclear Posture Review, issued in 2022 by the Biden administration, reaffirmed longstanding policy that “the United States will not use or threaten to use nuclear weapons against non-nuclear weapon states that are party to the NPT [Treaty on the Non-Proliferation of Nuclear Weapons] and in compliance with their nuclear non-proliferation obligations.” 1
While this language does not specifically reference Iran by name, Iran is the country that most accurately meets this description. The NPR states that “U.S. policy is to prevent Iran from acquiring a nuclear weapon,” 1 and the most recent iteration of the U.S. Nuclear Employment Strategy––issued in 2024––states that the United States “is prepared to use all elements of national power to ensure that outcome.” 2 In June 2025, the International Atomic Energy Agency (IAEA) issued a resolution finding that Iran was no longer in compliance with its NPT obligations. 3
While still limited, the DPRK has released more information about its nuclear and other weapons-related development compared to the past. This is likely aimed partly at domestic audiences to reinforce regime legitimacy, and partly at international audiences for deterrence purposes. When examining the official statements released after the six nuclear tests, the rationale for each test has gradually become firmer and more detailed, offering glimpses of how the DPRK frames the development and direction of its nuclear programme. For the fourth nuclear test, which it described as its first hydrogen bomb test, the DPRK provided a clearer timeline for issuing the test order. Kim Jong-un “주체104(2015)년 12월 15일 주체조선의 첫 수소탄시험을 진행할데 대한 명령을 하달하신데 이어 주체105(2016)년 1월 3일 최종명령서에 수표하시였다. [issued an order to conduct the first H-bomb test … on December 15, Juche 104 (2015) … and then signed the final written order on January 3, Juche 105 (2016)].”(e) The fourth nuclear test occurred on the 6th of January in 2016.(f) After the fifth nuclear test, the announcement further stressed the direction of its nuclear weapons development, stating that “핵탄두가 표준화, 규격화됨으로써 우리는 여러가지 분렬물질에 대한 생산과 그 리용기술을 확고히 틀어쥐고 소형화, 경량화, 다종화된 보다 타격력이 높은 각종 핵탄두들을 마음먹은대로 필요한만큼 생산할수 있게 되였으며 … [The standardization of the nuclear warhead will enable the DPRK to produce at will and as many as it wants a variety of smaller, lighter and diversified nuclear warheads of higher strike power with a firm hold on the technology for producing and using various fissile materials].”(g) Throughout all six tests, however, the emphasis has remained consistent on safe testing conditions and the self-defensive nature of the nuclear and missile programmes. (a,b,c,f,g,h)
Moreover, in comparing the DPRK’s nuclear force laws, the 2022 law is a more elaborated document than the 2013 “자위적핵보유국의 지위를 더욱 공고히 할데 대하여 [On Consolidating the Position of Nuclear Weapons State for Self-Defence]”.(d) The 2022 version provides clearer command-and-control provisions for nuclear use and repeatedly emphasizes the DPRK’s status as a ‘responsible nuclear state’.(i)
At the 13th Session of the 14th Supreme People’s Assembly, Kim Jong-un reiterated the rejection of the concept of denuclearization, stating that “《비핵화》라는 개념은 이미 그 의미를 상실하였습니다… 이제 《비핵화》를 하라는것은 우리더러 위헌행위를 하라는것입니다. 단언하건대 우리에게서《비핵화》라는것은 절대로, 절대로 있을수 없습니다. [The concept of denuclearization has already lost its meaning…Asking us to accept denuclearization now is as good as asking us to go against our Constitution… denuclearization is the last, last thing to expect from us].”(j)
Overall, the information the DPRK releases seems calibrated to serve its strategic purposes, offering enough detail to signal confidence and deterrence. At present, understanding the status of North Korea’s nuclear weapons development and related activities relies largely on open-source intelligence tools, particularly commercial satellite imagery.[1,2]
France has been increasingly transparent on its arsenal and doctrine over the years, even if it chooses not to discuss some issues for national security reasons 5.
Regarding the nuclear doctrine, it is made public through regular presidential speeches but also White Books or Strategic reviews which are updated regularly. France translates key documents in English and has organised events, for instance in the margins of the NPT Review Conferences, to explain and discuss the French doctrine 1. It has published detailed information 2, in particular in the NPT contexts, related to specific elements of the doctrine, for instance negative security assurances 1.
In addition, the French government funds the publication and translation of work on French nuclear deterrence which have informative purposes. It is the case for instance of books written by former or current officials, or of non-officials commissioned by the French government to popularise the French doctrine 6.
Concerning the arsenal, France does not give a precise number regarding its warheads, but a ceiling (less than 300) 3. It does not communicate at all on fissile material holdings, and prefers to emphasise the fact that the country has stopped producing fissile material for nuclear weapons and has dismantled its facilities 1. However, it is more forthcoming on information on delivery vehicles and platforms, with successive presidents updating the public on the number of ballistic missiles or cruise missiles that are being possessed by the French strategic forces, as well as the number of submarines and aircrafts that are dedicated to the nuclear mission (3 and 4. Information is also voluntarily supplied regarding modernisation programmes, in particular in order to inform the Parliament, which votes for credits for the deterrent. Since the early 2000s, information has been provided to the public on budgets, including regarding strategic systems and support missions for the nuclear deterrence mission.
More generally, France has stated that it supports transparency as a strategic risk reduction tool, and as long as it does not create prejudices for national security. It is seen as a confidence-building mechanism and a way to limit misperceptions and the risk of misunderstanding. In that sense, France takes part for instance in the Hague Code of Conduct against the proliferation of ballistic missiles but also other multilateral arms control mechanisms (space registration convention, UNROCA, …). 5
France has promoted and publicised some voluntary transparency gestures it took over the years, in particular the invitation of international visitors to its former fissile material production facilities, its former dismantled ground-based missile site, and its former nuclear test site in French Polynesia 1. It also held two transparency visits in Kourou, on the space launch site, as part of the implementation of the HCoC.
Pakistan started its nuclear weapons pursuit much later than its main rival India. After becoming overt nuclear weapon state, Pakistan consolidated its nuclear deterrent by developing number of delivery systems, mainly in the form of ballistic missiles and later the cruise missiles that could be launched from land, air, and sea. It has nevertheless maintained secrecy over number of nuclear delivery systems and warheads and has provided no transparency about its existing potential or future development plans. Pakistan however does provide ranges of its cruise and ballistic missiles.
Pakistan has not declared its nuclear use doctrine officially but has provided sufficient transparency in its nuclear policy through official statements and press releases by the military side. There are no clearly defined red lines, but its nuclear posture is considered credible and has been able to achieve the desired result during the past few crises with India, which remains its principal adversary.
For nuclear delivery systems, Pakistan has developed different types of ballistic and cruise missiles that are often labelled as dual-capable but are generally believed to be dedicated mainly for nuclear use. The command and control of these delivery systems is with the National Command Authority (NCA), which comprises of senior political and military leadership and is headed by the Prime Minister. The NCA structure clearly outlines the authority for nuclear use, which is the Prime Minister, and these have been well published to bring clarity in the command-and-control system.
Pakistan adheres to its bilateral commitment of notifying test of all ballistic missiles. It has maintained principled stance on Negative Security Assurances and wants a legally binding arrangement to be concluded amongst all the nuclear armed states at the Conference on Disarmament, Geneva.
On the issue of fissile material, it has not declared its fissile material stocks, and neither the capacity and location of these facilities. Several independent analysts have offered different estimates about Pakistan’s weapon capabilities, but these have never been endorsed by Pakistan. On the issue of limiting fissile material production, Pakistan has maintained a consistent position that any treaty negotiated to stop further production of fissile material must also take into consideration the existing asymmetries of stocks.
On nuclear security related issues, Pakistan remained actively involved in the US-Russia led Nuclear Security Summit process and provided sufficient transparency on the measures taken at the national level to ensure nuclear safety and security of all facilities in the country.
On the potential integration of artificial intelligence in the nuclear command and control and the delivery systems, it is likely that Pakistan would remain reluctant due to likely implications for strategic stability. As one of the active proponents of the restricting lethal autonomous weapons (LAWs), it is possible that it would resist the temptation of using new technologies in the nuclear systems.
The United States is the most transparent of the nuclear-armed states.
It is one of only a small handful of countries that has published historical and current data about the exact size of its nuclear stockpile. [1, 2, 3] In addition, the United States discloses detailed information regarding its current stockpile, nuclear-capable delivery vehicles, missile launches, deployment numbers and locations, nuclear doctrine, and modernization plans, among other key elements. [4, 5, 6, 7]
This high degree of transparency is primarily due to several factors:
The United States’ participation in arms control and risk reduction treaties (e.g. New START, which limits deployments of strategic warheads and launchers, and the 1988 agreement on the pre-notification of ballistic missile launches) that require and encourage notifications and disclosures. [8, 9]
The requirement of the Departments of Defense and Energy to justify funding requests to Congress, which can in turn interrogate and request additional information through update, testimony, or study. [10, 11, 12]
The United States’ robust watchdog, civil society, and media landscape, including government-funded agencies like the Government Accountability Office and the Congressional Budget Office, investigative journalists, and nongovernmental organizations that report on, request comment from, and critique government programs and plans. [13, 14]
A legacy culture of responsible transparency and open government, supported by legal mechanisms like the Freedom of Information Act, which allow researchers to access certain details about nuclear programs that would otherwise be classified.
A desire to contrast its own nuclear program with those of its less-transparent competitors, like Russia or China. [15, 16]
A belief that, as the National Nuclear Security Administration stated in 2024, that “Increasing the transparency of states’ nuclear stockpiles is important to nonproliferation and disarmament efforts, including commitments under the Nuclear Non-Proliferation Treaty, and efforts to address all types of nuclear weapons, including deployed and non-deployed, and strategic and non-strategic.” [3, 16]
Despite the United States’ relatively high degree of transparency regarding its nuclear forces, in recent years it is clear that the efforts have been made to curtail some of these elements. For example:
The United States is increasingly keeping secret more details about its nuclear forces. 17 For example, for many years the majority of the budget and characteristics of the upcoming B-21 Raider––the Air Force’s new nuclear-capable stealth bomber––were classified. 18
Since 2019, the United States has stopped declassifying the size of its nuclear stockpile and its number of dismantled warheads on an annual basis, instead electing to release this data on an ad hoc basis. 19 The denial of declassification requests in 2023 included the justification that “the Department of Defense and Department of Energy/National Nuclear Security Administration do not believe that [it] is in the best interest of the United States,” but did not provide any additional details. 20
The United States has selectively removed or omitted certain sensitive details from official documents after widespread public reporting and critique. For example, in the North Atlantic Treaty Organization’s Security Investment Program budget for Fiscal Year 2023, the U.S. Department of Defense included “the UK” among a list of countries slated for infrastructure modernization at “special weapons” storage sites––thus indicating the potential return of U.S. nuclear weapons to UK soil for the first time in 15 years. 21 Following an influx of scrutiny, the following year’s budget document for the same program did not include any country names. 22
Following Russia's unilateral suspension of New START in February 2023, the United States disclosed one final set of deployment-related treaty data from March 2023, but subsequently has not released any deployment data since then. [8, 23]
At the 8th Congress of the Workers’ Party of Korea in 2021, Kim Jong-un announced the modernization plan for the next five year to “핵기술을 더욱 고도화하는 한편 핵무기의 소형경량화, …전술핵무기들을 개발하고 초대형핵탄두생산도 지속적으로 밀고나감 [further advance nuclear technology, the miniaturization and lightweighting of nuclear weapons, the development of tactical nuclear weapons, and the production of ultra-large nuclear warheads].” This plan also include the “1만 5, 000㎞ 사정권안의 임의의 전략적대상들을 정확히 타격소멸하는 명중률을 더욱 제고하여 핵선제 및 보복타격능력을 고도화할데 대한 목표가 제시되였다. [goal to improve the preemptive and retaliatory strike of nuclear forces…within the 15,000 km]” and ”가까운 기간내에 극초음속활공비행전투부를 개발…수중 및 지상고체발동기대륙간탄도로케트개발사업을 계획대로 추진시키며 핵장거리타격능력을 제고하는데서 중요한 의의를 가지는 핵잠수함과 수중발사핵전략무기를 보유할데 대한 과업이상정되였다 [task to develop hypersonic gliding flight warhead, ground-based and sea-based solid-fueled intercontinental ballistic missiles, as well as nuclear-powered submarine and underwater-launch nuclear strategic weapon which are of important significance in raising the long-range nuclear striking capability].”(a)
Kim has stressed that the country will pursue “핵무장화의 급진적인 확대 [a rapid expansion of nuclearization]” and emphasized the important role of naval forces to perform as a part of “앞날에국가핵무력구성과 핵사용령역에서 일익을 굳건히 담당하는 믿음직한 력량으로 될것이라 [state nuclear forces and the realm of nuclear use in the near future].”(c)
Another five-year plan is expected to be included for the 2026 Ninth Party Congress.
France has announced publicly that since 2017, it has been committed to renewing its two nuclear components. The strategic oceanic forces will be equipped with a new increment of the M51 intercontinental ballistic missile, and the third generation of nuclear-powered ballistic missile submarines has been launched. The four submarines of the new class should enter into service starting from 2025. The airborne nuclear component will be equipped with new hypersonic cruise missiles (ASN4G) including new warheads. This missile is being developed by MBDA and should also become operational starting in 2035. It will be initially integrated on the Rafale F5 aircraft, and later on the Next Generation Fighter (NGF), an aircraft that should be produced in the framework of the European Future Combat Air System (FCAS) programme 1. Budgets and rationales are published by the Parliament on these programmes, with outputs from programme managers of the Ministry of Armed Forces. 2
Pakistan's modernisation plan mainly depends on India's actions and its evolving conventional and nuclear capabilities. Its missile delivery systems and fissile material production capacity are all aimed to neutralise or counter India's overall military advantage and to maintain strategic balance in the region. It therefore become difficult to predict what new weapon systems or facilities would be needed to achieve these objectives.
Yes, the UK government does disclose its high-level plans and strategic rationale for the modernisation of its nuclear arsenal, though it has simultaneously increased ambiguity around its operational details.
The UK's strategic rationale for modernising its deterrent is a direct response to a perceived ‘deteriorating security environment’. The 2023 Integrated Review Refresh explicitly states that the international context is more competitive and dangerous than at any time since the Cold War. It cites an ‘acute threat’ from Russia, an “epoch-defining and systemic challenge” posed by China, and the proliferation of nuclear weapons and disruptive technologies by states like North Korea and Iran.1
Plans for modernising nuclear weapon systems and the nuclear weapons complex are public and well-established. The UK has publicly stated it is:
Building four new Dreadnought-class SSBNs at BAE Systems Barrow shipyard to replace the current fleet of Vanguard-class ballistic missile submarines, with the first of class - HMS Dreadnought - expected to enter service in the early 2030s.
Planning to deploy the US designed and built Trident II D5LE SLBM as deployed on the Vanguard-class to be replaced by the D5LE2 from the 2040s.2
Purchasing 12 F-35A aircraft from the US to provide a ‘dual-capable’ (conventional and nuclear) air-launched nuclear capability using B61-11 US gravity bombs in support of NATO.
Designing a replacement warhead, known as Project Astraea (A21/Mk7) in close coordination with the US W93 warhead programme to replace the current UK design (Holbrook/Mk4A).3
Undergoing a massive, multi-billion-pound infrastructure modernisation as part of the Nuclear Warhead Capability Sustainment Programme to support the design and production of a new warhead. This includes the Project MENSA warhead assembly/disassembly facility at the AWE Burghfield site, a High Explosive Fabrication Facility, and the Future Materials Campus (FMC) to manufacture, store, and recover nuclear materials for warhead components at AWE Aldermaston.
Modernising all parts of the nuclear weapons complex including BAE Systems' shipyard in Barrow-in-Furness, the next generation of facilities at Rolls-Royce's Raynesway site in Derby, and the Royal Naval Armaments Depot (RNAD) Coulport to build new facilities to support Astraea.
Exploring options to re-establish a nuclear fuel cycle for reactor fuel for defence purposes.4
On fissile material production: The UK has not produced fissile material (highly enriched uranium or plutonium) for weapons since 1995 and maintains a moratorium on this. New facilities at AWE are not for producing new plutonium or uranium. The modernisation programme involves using the UK's existing stocks of fissile material.
The United States is highly transparent about its modernization plans for each element of its nuclear arsenal, including warheads, delivery systems, nuclear warheads production, nuclear command and control, and the facilities, networks, and workforce that underpin them.
This degree of transparency can primarily be attributed to the fact that while presidential administrations can issue decisions and guidance about alterations to U.S. nuclear forces, those alterations must be authorized and funds must be appropriated by Congress in order to execute them. As a result, presidential administrations must justify their proposals to Congress through detailed budgetary submissions, congressional testimonies, studies, and laws that require certain types of disclosures.
By combining all of these various sources, it is not difficult to obtain a comprehensive picture of nearly every aspect of the U.S. nuclear modernization program, with the exception of certain details or studies that remain classified (e.g. the Analysis of Alternatives report for the modernization of the intercontinental ballistic missile force, which would provide critical insight into the Department of Defense’s initial justifications for the program).
For example, the Department of Defense’s 2020 publication of the Nuclear Matters Handbook provides details on each warhead, delivery system, scientific and technical facility, and elements of nuclear command, control, and communications infrastructure that are currently being upgraded or modernized. 1 In addition, the Department of Energy’s annual Stockpile Stewardship and Management Plan provides comprehensive details on each element of the nuclear security enterprise, including budgetary information and upgrades to individual warheads and facilities. 2 Detailed annual budgetary information is disclosed through presidential and service budget requests, which Congress then interrogates, authorizes, and appropriates. [3, 4, 5] Despite a degree of classification for some aspects of nuclear modernization and justification, many documents are ultimately accessible through the Freedom of Information Act. 6
The DPRK does not disclose its total holdings, in each category, of low-enriched uranium, highly-enriched uranium, and plutonium. It does mention about the importance to increase production.
While no official records have been released by the DPRK government, expert estimates are primarily based on the plutonium production capacity of the 5 MWe reactor.(a)2 This reactor is believed to be capable of producing about 6 kg of plutonium per year.1 Moreover, the DPRK has claimed efforts to build an experimental light-water reactor in response to the 2009 April the presidential statement by the United Nation Security Council, “유엔안전보장리사회가 즉시 사죄하지 않는 경우 우리는…둘째로, 경수로발전소건설을 결정하고 그 첫 공정으로서 핵연료를 자체로 생산보장하기 위한 기술개발을 지체없이 시작할것이다 [In case the UNSC does not make an immediate apology, we will…Secondly, decide to build a light-water reactor power plant and begin immediately the technological development to ensure our own production of nuclear fuel].”(b)
The DPRK states the reactor is intended primarily for electricity generation, but the expert community has raised concerns that it could be repurposed for plutonium production.3 If it were operated on a weapons-sensitive fuel cycle, it could produce up to 20 kg of weapons-grade plutonium per year.2
Regarding uranium enrichment, as early as 2010 there were news reports about the DPRK’s “수천대규모의 원심분리기를 갖춘 [possession of thousands of centrifuges].”(c) More recently, during an inspection visit by Kim Jong-un to the Nuclear Weapons Institute, photos were released showing him touring the control room of a uranium enrichment facility.(f) Based on the number of centrifuges visible in those images, experts have estimated that the facility houses at least 2,000 centrifuges, though it remains unclear whether all of them are operational and if those are all centrifuges it possesses.5
France has not explained its decision not to communicate on its holdings of fissile material. It has stated in 2000 in the framework of the NPT Review Conference that it does not have any weapon-grade fissile material in excess of its military requirements 2. France has stated on many occasions that it has stopped the production of fissile material for nuclear weapons in 1992 (plutonium) and 1996 (highly enriched uranium). It dismantled its fissile material production factories in an irreversible fashion in the 2000s 1.
Pakistan being a late starter in its nuclear weapons pursuit believes that its major rival India has advantage in terms of fissile production capacity and the existing stocks. It has therefore opted to maintain ambiguity about its production capacity and the type of fissile material produced, or being produced to meet the future requirements.
The UK partially discloses its total holdings of low-enriched uranium, highly-enriched uranium, and plutonium. The UK “ceased the production of fissile material for explosive purposes” in April 1995.1 In 2000 the UK published a historical accounting of its plutonium production for defence purposes up to 1999.1 In 2006 the UK published a historical accounting of its production of Highly Enriched Uranium for defence purposes up to 2002.2 It has not updated the figures in these reports. The UK also provides the IAEA a statement of its annual figures for holdings of civil high-enriched uranium and civil depleted, natural and low enriched uranium in its civil nuclear fuel cycle.3
The UK submits regular reporting of civil fissile material holdings to the IAEA, typically monthly.4 Separately from day-to-day safeguards, the UK also provides to the IAEA a statement of its annual figures for holdings of civil high enriched uranium and civil depleted, natural and low enriched uranium in its civil nuclear fuel cycle under INFCIRC/549.3 This is a set of voluntary transparency guidelines established in 1998 under which participating states publish annual, public figures for their civil unirradiated plutonium (plus an estimate for plutonium in spent fuel), along with short policy statements. Some states, including the UK, have chosen to add civil HEU figures for the purposes of transparency.
The UK reiterated in 2010 that it was under no obligation to report the production, transfer or use of fissile material for defence purposes to the IAEA because such material is held outside the international safeguards regime. It is subject to a strict internal materials accountancy regime.5
The United States discloses its total holdings of different fissile materials at different degrees of transparency, depending on the type of material.
In 1998, the International Atomic Energy Agency (IAEA) published Guidelines for the Management of Plutonium (INFCIRC/549), for which the five nuclear weapon states agreed to publish annual statements of their holdings of civil plutonium. While INFCIRC/549 covers most categories of plutonium, certain categories––such as plutonium with an isotopic concentration of plutonium-238 exceeding 80 percent, plutonium on which IAEA safeguards have been exempted or terminated, or plutonium used in gram quantities or as a sensing component in instruments––are exempt. 1 The United States’ most recent declaration, from 2023, noted holdings of less than 0.05 metric tons of unirradiated separated plutonium produced during the course of manufacture or fabrication, 4.6 metric tons of plutonium contained in unirradiated MOX fuel, and 44.6 metric tons of unirradiated separated plutonium held elsewhere––all of which were roughly the same as the previous year’s figures.
INFCIRC/549 does not cover holdings of low-enriched or highly-enriched uranium (HEU), and the United States does not regularly provide any public information on these stocks. The most recent instance of the United States disclosing details about its HEU stocks was in 2016, and included data from between 1996 and 2013. The disclosure noted that as of September 30, 2013, the United States’ total HEU inventory was 585.6 metric tons, 499.4 metric tons of which was for “national security or non-national security programs including naval propulsion, nuclear energy, and science.” The disclosure also noted that “of the remaining 86.2 metric tons, 41.6 metric tons was available for potential down-blend to low enriched uranium or, if not possible, disposal as low-level waste, and 44.6 metric tons was in spent reactor fuel.” 3
The DPRK does not disclose information about the types of fissile material production or reprocessing facilities it possesses that are used for nuclear weapons purposes. There are limited mentioning by the DPRK’s state news agency regarding the rough location occasionally. For instance, the already known 5 MWe reactor according to the Agreed Framework signed between the DPRK and the USA in 1994 is located in 녕변 [Nyongbyon].(a,b)
There are also occasionally mentioning about the names of the facilities that produce fissile materials for nuclear weapons purposes. During the 2019 Hanoi Summit negotiation, the US state department official has mentioned that “What they [the DPRK] had offered in return was the dismantlement of the Yongbyon [Nyongbyon] nuclear complex.”1 There are also mentioning of 핵무기 연구소 [Nuclear Weapons Institute]. Kim Jong-un has paid two visits so far this year to inspect the nuclear-material production base and the Nuclear Weapons Institute.(d)
France stopped the production of plutonium for nuclear weapons in 1992 and highly enriched uranium in 1996. President Chirac announced during a TV interview that the Pierrelatte facility would close on 22 February 1996. 1 The decommission of the Pierrelatte enrichment plant started in 1997 and will continue until 2040. The dismantlement of the G1, G2 and G3 plutonium producing reactors at Marcoule has been completed 2. Moreover, France promotes the fact and has organised several visits for international observers on the former production sites. 3
Pakistan doesn't disclose information about the types of fissile material production or reprocessing facilities it possesses which that could be used for nuclear weapons purposes. Several unofficial reports have speculated about these facilities to understand Pakistan's fissile material production capacity but these estimates or their conclusions have never been endorsed by the official government sources.
The UK does not operate any fissile material production or reprocessing facilities for nuclear weapons purposes and “ceased the production of fissile material for explosive purposes” in April 1995. 1
Production of HEU for defence programmes at the UK’s Capenhurst Plant ended in 1962. Since then the UK has received HEU for both its warhead programme and naval reactor programme through exchanges of special nuclear material with the US Department of Energy under the 1958 Mutual Defence Agreement. In the 1960s, the plant was modified to produce Low Enriched Uranium (LEU) for civil nuclear power reactors until it ceased operations in 1982.
The UK has operated three reprocessing facilities at its Sellafield nuclear site: the First Generation Reprocessing Plant (B204) from 1952 to 1964 to extract plutonium from spent nuclear fuel for the UK’s nuclear weapon programme. It was replaced by the Magnox Reprocessing Plant (B205), which operated from 1964 to 2022. The Magnox Reprocessing Plant reprocessed spent fuel from UK Magnox nuclear reactors for civilian purposes until 2022 and for military purposes until 1995. It is now in cleanup/decommissioning. The Thermal Oxide Reprocessing Plant (THORP) was a civil reprocessing plant that operated from 1994-2018 but did not separate plutonium for the UK nuclear weapons programme. 2
The Calder Hall Magnox power station at the Sellafield site consisting of four dual-purpose reactors began operations in 1956 for commercial electricity generation and plutonium production for defence needs. The Chapelcross power station in Southern Scotland operated on the same basis as Calder Hall from 1958. Following the UK government’s announcement in 1995 that it would end production of fissile material for the nuclear weapons programme, Calder Hall reactors were brought under Euratom safeguards and made liable to inspection under the terms of the safeguards agreement between the UK, Euratom and the IAEA. 1 Calder Hall closed in 2003.
Chapelcross reactors continued to produce tritium for nuclear weapons and were not subject to international safeguards inspection. However, the 1998 Strategic Defence Review announced that all reprocessing of spent fuel from defence reactors at Chapelcross would be conducted under Euratom safeguards and made liable to inspection by IAEA. Chapelcross ceased operations in 2004.
The Department of Defense’s Deputy Assistant Secretary of Defense for Nuclear Matters published a revision to its Nuclear Matters Handbook––a comprehensive overview of the U.S. nuclear deterrent––in 2020. The latest edition includes a detailed examination of the National Nuclear Security Administration’s Nuclear Security Enterprise, which spans eight sites: Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Sandia National Laboratories, Kansas City National Security Campus, the Pantex Plant, the Savannah River Site, the Y-12 National Security Complex, and the Nevada National Security Site. 1
The Nuclear Matters Handbook also includes details about the “strategic materials” that are managed at each site, and their relation to the nuclear deterrent: the Los Alamos National Laboratory is currently responsible for managing plutonium pits––the core of a nuclear weapon that initiates the chain reaction required for a nuclear explosion––the Y-12 complex is responsible for managing uranium and lithium, and the Savannah River Site is responsible for managing tritium. It also notes future plans to convert the Mixed Oxide Fuel Fabrication Facility at the Savannah River Site to a plutonium processing facility that will be capable of producing at least 50 pits per year, and the recapitalization of a plutonium facility at Los Alamos National Laboratory to produce at least 30 pits per year. The handbook additionally notes that the U.S. government currently has no capacity to enrich uranium domestically, but that plans are being developed to re-establish this capability. 1
The DPRK reveals limited information on occasions such as missile launch tests, visits to key military facilities, and major national events, including the recent military parade marking the 80th founding anniversary of the Workers’ Party of Korea.(d) It is believed by the expert community and intelligence agencies that the DPRK has achieved a level of miniaturization of its nuclear warheads sufficient for mounting them on various delivery systems, ranging from short-range ballistic missiles to intercontinental ballistic missiles, as well as submarine-launched ballistic missiles.[1,2,3,4]
The DPRK has previously claimed to have conducted its third nuclear test with a “소형화, 경량화된 원자탄 [smaller, lighter atomic bomb].” and has emphasized the importance of developing “정밀화, 소형화된 핵무기들과 그 운반수단들을 더 많이 만들… [more precise and miniaturized nuclear weapons and their delivery systems and by advancing nuclear weapons technology].”(a,b) Moreover, in 2021, Kim Jong-un stated the intention to “이미 축적된 핵기술이 … 전술무기화 [make the existing nuclear weapons tactical ones].”(c)
Overall, information from the DPRK regarding its delivery vehicles remains limited, making it difficult to determine which systems are operational and which are assigned for nuclear missions. The DPRK occasionally implies such roles in news reports related to weapon testing. For instance, according to the DPRK’s only English-language newspaper, The Pyongyang Times, “Guiding the test-fire of Padasuri-6 ground-to-sea missile to be furnished for the Navy and the test launch of the submarine-launched strategic cruise missile Pulhwasal-3-31… made sure … that the Navy was armed with nuclear weapons and that the sphere of operation of the state nuclear deterrent was expanded in a diversified way.”(d)
Since the White Book on Defense of 1972, France has been open about the various components of its nuclear deterrent, and in particular has indicated which types of delivery vehicles it possessed and operated 1. Official documents and speeches have therefore confirmed that France currently operates intercontinental submarine-launched ballistic missiles which are carried by its nuclear submarine and airborne cruise missiles which are carried by its Rafale aircrafts (2 and 3. The submarine-launched ballistic missiles’ range is not specified but estimated between 6000 and 10000 km. The airborne cruise missile is estimated at around 500 km. 4 Both delivery vehicles are only dedicated to the nuclear mission.
Historically, it also held nuclear ground-launched ballistic missiles of various types and gravity bombs but those have been dismantled as announced in various documents. 1
Pakistan has classified all of its nuclear-capable delivery vehicles as dual-capable to retain the option of their use for conventional purposes. These systems are are also classified in terms of specific ranges which gives some idea of their likely employment. These ranges, however, are intended to cover the nature of threat from its eastern neighbor and does not go beyond 2750 kms.
The UK has one nuclear weapons delivery system comprising US Trident II (D5) SLBMs deployed across a fleet of four Vanguard-class UK SSBNs. The UK government has publicly stated that the Vanguard-class SSBNs will be replaced in the 2030s with four Dreadnought-class SSBNs currently under construction 1.
The UK has publicly stated that it participated in the US programme to upgrade the Trident II (D5) SLBMs to the D5LE (Life Extension) version (2). The US has now embarked on a second life extension programme (D5LE2) to extend the life of the missile to the 2080s (3).
The UK does not deploy any other types of nuclear weapons or any other nuclear delivery vehicles. The UK's last air-launched nuclear weapons (WE177 gravity bombs) were withdrawn in 1997(4).
Although primarily intended to describe plans for warhead modernization, infrastructure recapitalization, and workforce development, the U.S. National Nuclear Security Administration's annual Stockpile Stewardship and Management Plan includes a table of all current warheads and their associated delivery systems in the U.S. stockpile. For each warhead type, the table lists each delivery system that can carry that particular warhead, lists the mission (distinguishing between strategic and nonstrategic weapons), and lists which service (Air Force, Navy, or select NATO forces) is responsible for their deployment.
In the Fiscal Year 2025 Stockpile Stewardship and Management Plan, the United States includes the following categories of nuclear-capable delivery systems: Minuteman III intercontinental ballistic missile; Trident II D5 submarine-launched ballistic missile; F-15; F-16; certified NATO aircraft; B-2 bomber; F-35; and B-52 bomber. 1
There are no official records released by the DPRK government regarding the number of nuclear-capable (including dual-capable) delivery vehicles it possesses. The DPRK news agencies focus on reporting missile test launches or the unveiling of new relevant weapons systems. During the recent military parade marking the 80th founding anniversary of the Worker’s Party of Korea, the Hwasongpho-20 ICBM was presented as “최강의 핵전략무기체계 [the most powerful nuclear strategic weapon system]”.(a)
There is also a lack of unofficial estimates on their numbers; instead, most analyses focus on the ranges and types of delivery vehicles and whether they are under development or in operation. [1,2,3]
The 1972 Livre Blanc gave information about the number of ballistic missiles in service as well as nuclear squadrons 1. President Mitterrand gave more precise information in his speech of 1994 2. President Hollande announced in 2015 that France holds three sets of 16 M51 intercontinental submarine-launched ballistic missiles (48) and 54 nuclear air-launched cruise missiles 3. In its latest transparency report, France confirmed that it holds three sets of 16 M51 submarine-launched ballistic missiles (48) and 54 nuclear air-launched cruise missiles (ASMPA) 4.
Pakistan has never disclosed the number of delivery vehicles for its land, air, and sea-based nuclear capabilities or the number of dual-capable delivery vehicles. It has not maintained separate inventory of nuclear-capable missiles and labels all nuclear capable delivery platforms as dual-capable.
The UK deploys a single nuclear delivery system - the Trident II (D5) SLBM. The UK originally purchased title to 65 Trident SLBMs from the US under the 1963 Polaris Sales Agreement amended for procurement of Trident in 1982 1. This was reduced to 58 in 1998 (2). The missiles are designed, produced, stored, and maintained in the US when they are not deployed on the UK’s fleet of four Vanguard-class SSBNs. The UK pays an annual contribution to the continued maintenance of the missile stock (3).
Some UK missiles have been used in live test fires. Each Vanguard submarine underwent a Demonstration and Shakedown Operation (DASO) upon commissioning, culminating in a live test fire of an unarmed Trident missile at the US missile test range at Port Canaveral, Florida. The process is repeated after each submarine is recommissioned into operational service following a multi-year mid-life overhaul and refuelling. The UK had test fired eleven missiles as of January 2017 (4).
In 2010 the government’s Strategic Defence and Security Review stated it was reducing “the number of operational missiles the Vanguard-class submarines to no more than eight” but gave no further details (5). This statement was repeated in the 2015 Strategic Defence and Security Review (6). The change was completed in January 2015 (7).
The 2021 Integrated Review stated that the government intended to extend its “long-standing policy of deliberate ambiguity and no longer give public figures for our operational stockpile, deployed warhead or deployed missile numbers.” (8) The 2025 Strategic Defence Review and the 2025 National Security Strategy provided no details on missile numbers or deployments.
The government stated in 2021 that the UK had sufficient Trident II D5 missiles for its needs” (9). The UK only deploys nuclear warheads on its Trident missiles.
As a party to New START––a US-Russian treaty limiting numbers of deployed strategic warheads and launchers––until March 2023 the United States disclosed its total inventory of nuclear-capable strategic launchers, including intercontinental ballistic missile launchers, submarine-launched ballistic missile launchers, and heavy bombers, on a bi-annual basis. 1 These figures were published in aggregated format on the U.S. Department of State's website, and the disaggregated data was available upon request from the U.S. Department of State. In addition, as New START focused on counting warheads and launchers, these figures did not include the total numbers of US delivery systems.
When procuring new nuclear-capable delivery systems, the United States typically discloses how many units of that system it intends to purchase. For example, the Milestone B procurement decision for the United States' new Sentinel ICBM, acquired through a Freedom of Information Act Request, noted that the United States' acquisition plan accounted for purchasing 659 units of the Sentinel. 2 It is not common practice, however, for the United States to disclose the number of missiles remaining in its inventory as these units eventually get depleted through regular flight tests and maintenance.
In addition, U.S. Air Force web-based fact sheets and its Notice of Intent to Prepare an Environmental Impact Statement for its incoming B-21 Raider heavy bomber indicates that the U.S. will purchase a “minimum of 100 aircraft.” [3, 4] In addition, officials occasionally state the number of delivery vehicles of particular types that are present in the U.S. arsenal. For example, at a conference in March 2025, the Commander of U.S. Strategic Command advocated for the Air Force to purchase 145 B-21 bombers instead of 100, which “gives us 220 bombers when the [B-52s] are included.” 5
During the visit to Unmanned Aeronautical Technology Complex and the detective electronic warfare research group in March 2025, Kim Jong-un emphasized that “무력현대화건설에서 무인장비와 인공지능기술분야는 최우선적으로 중시하고 발전시켜야 할 부문 [in the effort to modernize the armed forces, the sectors of unmanned equipment and AI technology must be regarded as top priorities for development]” and that “지능화된 무인기들을 군사력의 주요수단으로 리용하기 위한 경쟁이 가속화되고 군사활동에서 그 사용범위가 부단히 확대되고있는 현대전의 추이에 맞게 이 사업의 가급적발전을 도모하기 위한 국가적인 전망계획을 정확히 작성하고 중장기적인 사업으로 인내성있게 강력히 추진해나가는것이 중요하다 [as the competition to use AI-enabled drones as major military assets is accelerating and the scope of their use in military activities is constantly expanding in modern warfare, it is important to formulate a long-term national plan to promote this rapid development and to push it forward vigorously and patiently as a mid- to long-term project.]”(d)
At the opening ceremony of the Arms Equipment Exhibition in October 2025, Kim stressed the importance for “인공지능기술을 비롯한 최신과학기술들이 적극 도입되여 전쟁수행능력의 견지에서 현행은 물론 미래의 전장에 대한 적응가능성도 확충하게 된것… [actively introducing AI and other cutting-edge technology which could not only expand our warfighting capabilities but also our adaptability to current and future battlefields.].”(e)
Moreover, academic papers shows that DPRK is studying how to measure distance and recognize obstacles when operating autonomous robots and is researching improvements in detection of intrusive cyber operations via artificial neural networks and genetic algorithms.(b,c) [1,2,3,4]
Regarding the use of AI on defense matters generally, French Defense Minister Florence Parly has indicated that the development of new technologies by France would be pursued following three principles: "abiding by international law, maintaining a sufficient human control, and ensuring the permanent responsibility of the chain of command." 1
In 2022, France supported a joint statement with the United Kingdom and United States according to which the three states "will maintain human control and involvement for
all actions critical to informing and executing sovereign decisions concerning nuclear weapons employment". 2
Pakistan has not disclosed its policies and operational practices regarding the use of artificial intelligence in systems related to the development, deployment, and employment of nuclear weapons, including the systems related to early warning and nuclear command and control.
Pakistan is also in the process of learning and understanding the implications of integrating new technologies into the military systems. However, due to the sensitivities associated with the potential use of artificial intelligence in nuclear weapons and their associated systems, there is a likelihood that such technologies may not be integrated in the near future.
There is no official UK government statement, parliamentary record, or defence policy document that describes the application, limits, or governance of artificial intelligence in relation to: the UK’s nuclear command, control and communications (C3) system, early-warning or decision-support systems, or the development, targeting, or employment of nuclear weapons.
However, the UK government’s 2022 Defence Artificial Intelligence Strategy stated that the UK “must shape global AI developments to promote security, stability and democratic values” and that “We will ensure that – regardless of any use of AI in our strategic systems – human political control of our nuclear weapons is maintained at all times. We strongly encourage other nuclear states to make a similar commitment.”1 This was reiterated in 2023.2
When asked in parliament in 2025 “if artificial intelligence has been used to support (a) routine operations and (b) policy in relation to nuclear capability”, the government replied “The delivery of defence capabilities enabled by artificial intelligence (AI) will be ambitious, safe and responsible. Research to identify, understand, and mitigate against risks of applying AI for sensitive defence affairs is underway. Routine nuclear deterrence operations continue to be conducted in accordance with the highest standards and controls. Regardless of any potential application of artificial intelligence in our strategic systems, we will ensure human political control of our nuclear weapons is maintained at all times”.3
In December, the House of Lords ‘Artificial Intelligence in Weapon Systems Committee’ published its report.4 The report noted that a key element in regulating autonomous weapons systems “will be prohibiting the use of AI in nuclear command, control and communications” (p. 4. In its response to the report, the UK government added “The UK is at the forefront of work internationally to reduce the risk of nuclear conflict and enhance mutual trust and security, and will continue to promote and engage with international dialogue aimed at identifying and addressing crucial AI-related strategic risks”.5
The United States’ Nuclear Posture Review––generally issued by each successive Presidential administration––describes the conditions under which U.S. nuclear weapons might be used, and describes U.S. nuclear policy, posture, and force structure, and their interaction with emerging technologies like artificial intelligence (AI). The most recent iteration–– published in 2022––states that “[i]n all cases, the United States will maintain a human ‘in the loop’ for all actions critical to informing and executing decisions by the President to initiate and terminate nuclear weapon employment.” 1 The Commander of U.S. Strategic Command testified to Congress in March 2025 that “AI will remain subordinate to the authority and accountability vested in humans,” although he did note that the service will use artificial intelligence and machine learning capabilities “to enable and accelerate human decision-making.” 2
The ultimate decision to use nuclear weapons, however, is one of the only areas relating to nuclear weapons where AI does not presently––or soon will––play an active role. The Department of Energy’s “Artificial Intelligence Strategy,” published in October 2025, and the National Nuclear Security Administration’s “Artificial Intelligence for Nuclear Deterrence Strategy,” published in 2023, both provide details as to how AI is being integrated into the nuclear mission. Of particular note is that AI is increasingly being used to support the stockpile stewardship mission by enhancing the United States’ modeling and simulation capabilities, by accelerating and automating the manufacture of systems needed for nuclear deterrence, and by assisting with the maintenance of nuclear weapon systems as they age. [3, 4]
The U.S. does not disclose the various ways in which AI is being integrated into parts of its early warning and nuclear command, control, and communications (NC3) infrastructure, although public statements from officials involved in the NC3 modernization process indicate that such integrations are indeed occurring. [2, 5]