The prohibition on possession and stockpiling
At the beginning of 2023, the nine nuclear-armed states had a combined inventory of approximately 12,512 nuclear warheads, which is evidently not compatible with the TPNW’s prohibition on possession and stockpiling of nuclear weapons. An estimated 9,576 of the total inventory are stockpiled warheads that are available for use by the military. The remaining 2,936 warheads had previously been retired and are awaiting dismantlement in Russia and the United States.
The Nuclear Weapons Ban Monitor collaborates with the Federation of American Scientists’ Nuclear Information Project to estimate and analyse global nuclear forces. The world’s nuclear warhead inventories at the beginning of 2023 are shown in animation above and figure below. China, India, North Korea, Pakistan, and Russia continued to expand their nuclear arsenals in 2022, bringing about a corresponding increase in the world’s total stockpile of warheads available for the use by the military, from 9,440 warheads in January 2022 to, 9,576 warheads in January 2023. These stockpiled warheads have an estimated collective yield of approximately 2,025.6 megatons (MT), which is more than 135,000 times the approximate yield of the 15-kiloton (Kt) bomb that destroyed Hiroshima in 1945.
Combined, the United States and Russia now possess approximately 89% of the world’s total inventory of nuclear weapons, and 86% of the stockpiled warheads available for use by the military. These percentages are likely to shrink over the coming years as other states increase their nuclear arsenals.
While the number of stockpiled nuclear warheads available for use increased in 2022, the world's total inventory of warheads decreased by approximately 193 from 12,705 warheads in early 2022 to 12,512 in early 2023. This reduction is, however, only due to Russia and the United States dismantling a small number of previously retired nuclear weapons during the course of 2022.
As shown in the chart below, the total number of nuclear weapons in the world is slowly decreasing each year, almost entirely due to the dismantlement of retired warheads by Russia and the United States. But, scratching below the surface of the data yields a much bleaker picture: the global number of stockpiled nuclear weapons available for use has been steadily increasing since around the year 2017, when it reached an all-time low of 9,227 warheads, and is expected to continue to do so. Meanwhile, the number of warheads dismantled each year appears to be decreasing. As illustrated by the graph below, this means that we could soon reach a point where the total number of nuclear weapons in the world will actually increase for the first time since 1986.
Estimates of nuclear warhead inventories can fluctuate from year to year depending on a variety of factors like routine maintenance, the changing pace of warhead retirement, and modernisation schedules. As a result, it is more appropriate to consider the general trends of each country’s inventory over a multi-year period. As mentioned above, China, India, North Korea, Pakistan, and Russia are all generally increasing the sizes of their nuclear stockpiles. The stockpiles of France, Israel, and the United States are generally stable, although the United States’ multi-year modernisation programme will eventually result in a slightly smaller stockpile with more capable warheads upon completion. The UK government in 2021 announced a significant increase to the upper limit of its warhead inventory compared with previous plans, but there is no publicly available evidence to indicate that such an increase has begun.
Countries are increasingly, and unnecessarily, withholding information about their nuclear arsenals from their publics, allies, and adversaries. In particular, states that had previously been more transparent about their nuclear arsenals, including the United States and the United Kingdom, recently decided to no longer provide details of the sizes of their nuclear stockpiles or the numbers of warheads they have deployed. In 2022, in a reversal from the previous year, the Biden administration did not disclose the size of the US nuclear stockpile or the number of warheads dismantled. The UK government said it would no longer disclose how many warheads it deploys. This trend of increased nuclear secrecy poses challenges for understanding trends in nuclear arsenals, undercutting efforts to increase transparency. A lack of clarity as to nuclear stockpiles, deployments, and employment policies can lead to worst-case assumptions about how states will develop or use nuclear weapons in the future, thereby exacerbating the arms race and increasing the possibility of miscalculation.
Additional information about global nuclear arsenals can be found on the ‘Status of World Nuclear Forces’ page on the Federation of American Scientists’ website.
Deployment and delivery systems
Of the global total of stockpiled warheads in early 2023 a total of 3,804 were at all times deployed on siloed and mobile missiles, at bomber bases, and on nuclear-powered ballistic missile submarines (SSBNs), while the remaining 5,772 warheads were held in reserve. As shown in the table below, only France, Russia, the United Kingdom, and the United States currently deploy warheads on delivery vehicles and at bases with delivery vehicles. It is believed that China, India, Israel, North Korea, and Pakistan likely keep all of their nuclear warheads in central storage during peacetime.
Around 1,950—or more than 50% of the deployed warheads—are deployed on SSBNs. At all times, a significant number of nuclear warheads are carried through the world’s oceans on SSBNs on active patrol, ready to be launched on short notice. France, Russia, the United Kingdom, and the United States deploy at least one SSBN each at sea at all times and can increase their numbers of deployed submarines during times of heightened tensions. For example, in response to Russia’s invasion of Ukraine, France briefly practiced deploying three SSBNs concurrently, rather than just one. As of January 2023, the United States was operating 14 SSBNs capable of carrying nuclear weapons while Russia was operating 11, China 6, the United Kingdom 4, France 4, and India 1 (with two more being fitted out). North Korea has one ballistic missile submarine (SSB) which is not thought to be currently operational. Russia also has attack submarines that can launch nuclear weapons, as does Israel.
Most SSBNs can carry a very large number of warheads because their missiles can deliver multiple independently-targetable re-entry vehicles (MIRVs). This means that the total firepower onboard a single SSBN can be larger than the entire arsenal of a lesser nuclear-armed country. Table H above describes these relationships in more detail for each nuclear-armed country that deploys SSBNs.
In addition to submarines, the nuclear-armed states operate a wide variety of delivery vehicles from which they can launch nuclear weapons, including siloed and mobile missiles, heavy bombers, tactical aircraft, surface ships and naval aircraft, and defensive systems. These systems all have vastly different characteristics, and thus, each country generally operates a unique combination of delivery systems in accordance with their respective strategies. The table below provides an overview of the diversity of nuclear-capable delivery vehicles in each nuclear-armed state’s arsenal, and the breakdown of the number of nuclear warheads that are assigned to each type of delivery vehicle. Russia has by far the most types of nuclear-capable delivery systems.
Explanation for the table on delivery vehicles:
A The table contains the best available information on types of nuclear-capable delivery vehicles currently fielded by each nuclear-armed state, as well as the estimated numbers of nuclear warheads (wh) that they have assigned to the delivery vehicles in each category. Some of the delivery systems listed in the table are currently deployed with warheads, but others are not. The table uses some national designations, and some US/NATO designations. It is possible that certain systems in the table are nearing retirement, or that they are nearing entry intro the respective state's nuclear forces, but had not yet been declared fully operational by the beginning of 2023.
B The total for Pakistan includes 8 warheads that are not yet assigned to delivery vehicles, but which are thought to have been produced eventually to arm delivery vehicles once they become operational.
C The total for India includes 20 warheads that are not yet assigned to delivery vehicles, but which are thought to have been produced eventually to arm delivery vehicles once they become operational
D It is uncertain which of North Korea’s missiles are assigned nuclear weapons and are operational.
Non-strategic nuclear weapons
Nuclear-armed states are generally moving away from megaton-level yields in favour of more accurate lower-yield warheads, although some analysts suggest that this could make nuclear weapons more ‘usable’, potentially lowering the threshold for nuclear use as a consequence.
Russia, the United States, North Korea, and Pakistan officially possess so-called tactical, or non-strategic, nuclear weapons that are intended to be used for shorter-range strike missions. There is, however, no universally accepted definition for what officially constitutes a ‘tactical’ nuclear weapon, and a common misconception is that all such weapons have lower yields and shorter ranges. The reality is much less clear: tactical nuclear weapons can have a wide range of yields and ranges; and a shorter-range weapon might be considered ‘non-strategic’ in US and Russian arsenals but ‘strategic’ in French, Indian, and Pakistani arsenals. The United Kingdom is the only nuclear-armed state that does not have nuclear weapons that can be considered non-strategic. Furthermore, the United States is the only nation known to deploy non-strategic warheads in other countries; the other nuclear-armed states are believed to keep their non-strategic warheads in central storage during peacetime.
Given Russia’s invasion of Ukraine in 2022, Russia’s sizable stockpile of non-strategic nuclear weapons is of particular concern. Russia possesses approximately 1,816 such weapons for use by naval, tactical air, and missile defence forces, as well as in the form of short- and medium-range ballistic missiles. It is likely that all of these warheads are kept in central storage, and at the time of writing, there was no indication that Russia had changed that. Nevertheless, tactical nuclear weapons are considered the most likely to be used if Russia ever decided to use nuclear weapons in the Ukraine war. Even the use of a lower-yield tactical nuclear weapon could immediately trigger a dramatic escalation of nuclear tensions.
It is of further concern that several nuclear-armed states are placing increased emphasis on non-strategic nuclear weapons in their nuclear doctrine. Russia has added several types of non-strategic nuclear weapons, and North Korea declared in 2021 that it would work to ‘make nuclear weapons smaller and lighter for more tactical uses’, and it continued to develop and deploy those capabilities throughout 2022.5 Many analysts believe that this increased emphasis on nuclear warfighting could lower North Korea’s nuclear threshold and increase the risk of nuclear use at the outset of a conflict.
Article 1(1)(a) - INTERPRETATION
Each State Party undertakes never under any circumstances to: [...] possess or stockpile nuclear weapons or other nuclear explosive devices.
- The prohibition on possession of any nuclear weapon or other nuclear explosive device under Article 1(1)(a) makes it illegal to have a nuclear weapon or other nuclear explosive device.
- Possession does not require legal ownership.
- One nuclear weapon or other nuclear explosive device is sufficient to constitute a stockpile.
- The prohibition on possession covers activities such as maintenance and deployment of nuclear weapons or other nuclear explosive devices. Indirectly, it also acts to render deterrence practices unlawful.