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The Nuclear Transparency Inventory (NUTRI) catalogues the transparency policies and practices of all nuclear-armed states regarding their nuclear arsenals and related facilities and fissile materials.
NUTRI provides factual summaries based on official government disclosures, with links to all the original sources to enable easy verification.
Below, we set out the methodology used to compile the NUTRI data.
The NUTRI ‘transparency categories’ are policy areas relating to the transparency of nuclear arsenals that BASIC identified as priorities for the international nuclear policy community based on extensive consultations between 2024 and 2026.
To define these categories, BASIC engaged with nuclear weapons policy specialists from dozens of UN member states, think tanks, academia, and other civil society organisations. They were asked to complete an online survey about their priority areas relating to nuclear transparency, and we followed up with invitations to individual interviews, either online or in-person.
To elicit further input from governmental and civil society experts, BASIC hosted a total of five side-events at the 2024 and 2025 Preparatory Committee meetings of the Nuclear Non-Proliferation Treaty (NPT) and at the 2026 NPT Review Conference. These events also sought input for the NPT Monitor, another project from BASIC’s Non-Proliferation and Disarmament Programme. The NUTRI website addresses twelve transparency categories at launch, and twelve additional categories will be added in the second half of 2026, for a total of 24.
To ensure the consistency and comparability of data across all nuclear-armed states, none of the NUTRI transparency categories are based on obligations deriving from the NPT, since several nuclear-armed states are not parties to the Treaty. In most cases, however, the categories are directly relevant to ongoing discussions in the NPT community.
For each transparency category, NUTRI starts by asking a simple, yes/no question about whether or not the country in question discloses information in this area, eg. ‘Does country X disclose information about category Y?’. The country experts that BASIC recruited to conduct the research (see below for details) also had the option to respond ‘partially’. These baseline responses are reflected in the data table. The country experts then expanded on these answers to provide more context and factual explanation. Although total objectivity is never possible, we have done our best to be rigorous and consistent in terms of the criteria applied.
The current NUTRI transparency categories and their corresponding questions are as follows:
Delivery vehicle numbers
Does this country disclose the total number of nuclear-capable (including dual-capable) delivery vehicles it possesses?
Delivery vehicle types
Does this country disclose the different types of nuclear-capable (including dual-capable) delivery vehicles it possesses?
Doctrine on employment of nuclear weapons
Does this country disclose its policy regarding when the employment of nuclear weapons would be considered?
Fissile material facilities
Does this country disclose the types of fissile material production or reprocessing facilities it possesses that are used for nuclear weapons?
Fissile material stocks
Does this country disclose its total holdings of low-enriched uranium, highly enriched uranium, and plutonium?
Integration of AI
Does this country disclose its policies and operational practices regarding the use of AI in nuclear weapon systems?
Modernisation plans
Does this country disclose plans for the modernisation or development of its nuclear arsenal (including warheads, fissile material, and delivery systems) and explain the strategic rationale for those plans?
Negative security assurances
Has this country issued a negative security assurance (NSA), committing not to use nuclear weapons against non-nuclear-armed states?
Pre-notification of space launches, missile tests, and nuclear exercises
Does this country issue advance notice of missile tests, space launch activities, and military exercises involving nuclear and dual-capable weapons systems?
Role of non-nuclear strategic technologies in nuclear doctrine
Does this country disclose how it accounts for, and responds to, strategic, non-nuclear technologies in its doctrine on the employment of nuclear weapons?
Warhead numbers
Does this state disclose the total number of nuclear warheads in its arsenal, including those that are active / deployed / in storage / awaiting dismantlement?
Warhead yields
Does this country disclose the explosive yields of its nuclear warheads?
BASIC recruited nine ‘country experts’ to survey the landscape of transparency policies and practices — one for each nuclear-armed state. The experts all have extensive professional experience analysing the nuclear weapons policies of their assigned state.
The nine experts were tasked with gathering data on official, public disclosures by their assigned states regarding the transparency categories outlined above.
To ensure all relevant sources are captured, we recruited experts who are citizens and/or are fluent in the official language(s) of their assigned state.
To enable blind peer-review of the data that will be added to NUTRI later in 2026, we are not revealing the names of the country experts at this initial stage.
After the country experts completed their survey, each national dataset was subjected to a double-blind peer review by another country-specific nuclear weapons expert.
The country experts then responded to the reviewers’ feedback based on the NUTRI criteria. The final datasets were edited by BASIC for consistency and suitability for the interactive NUTRI website.
The country experts were instructed to gather information solely from official government sources. Sources were considered ‘official’ when the following three questions were answered affirmatively:
The exception to this rule is NUTRI’s approach to Israel, which practices what is commonly known as ‘nuclear opacity’. That is, Israel has a strict, long-standing policy of refusing to confirm or deny anything about its nuclear weapon capabilities.
Nonetheless, as explained on the country page for Israel, ‘there has been a broad international consensus for more than half a century that [Israel] was the sixth state to develop nuclear weapons, having possessed them since the late 1960s or the early 1970s.’
NUTRI therefore applies a unique methodology to analyse Israel’s nuclear transparency policies. It reports what is publicly known about the Israeli nuclear weapons programme based on the best available historical research. This includes analysis based in large part on US or UK government sources and disclosures. We also discuss moments in Israeli political life where the veil of ‘opacity’ has been (partially) lifted, through public statements from senior Israeli government or military officials (or ex-officials) that convey messages widely seen as referring to Israel’s nuclear weapons capabilities. This approach aligns with the broader NUTRI objective of focusing specifically on the nuclear armed states’ various approaches to transparency.
For each transparency category, the country experts answered a yes/no question about whether their assigned state discloses information in that policy area. Experts also had the option to answer ‘partially’. These designations can be contextual and subject-specific, of course, but we have tried to be consistent in terms of the criteria applied.
An answer of ‘yes’ implies that for the most part, a government discloses the core elements of policies and practices in the policy area, as we have defined it. An answer of ‘no’ implies a government releases very little or no information in that area. An answer of ‘partially’ implies a government discloses some aspects of its policies or practices through official channels, but retains a degree of opacity or ambiguity on other aspects of the relevant policy area.
For each category, experts were instructed to submit their responses three times, at three different ‘levels’ of detail, comprising:
These three data levels are published in different formats across the NUTRI website, allowing users to browse countries or compare data at whatever level of detail is useful.
The country experts were asked to provide URLs of official sources where available. For official government disclosures that were never available online, or that were previously available but have now been removed or have become inaccessible for any reason, we sought to include exact copies of the original resource where it has been republished by other organisations.
In a small number of instances we provide links to government disclosures which have been made in response to freedom of information requests to civil society organisations.
As well as aiming to provide original URLs for all sources cited, we are working to progressively archive all resources via a public archive, the Wayback Machine. Over time, we will convert all URLs on the NUTRI site to the Wayback version, as this includes both a link to an archived version and the original URL, so readers can choose to access the resource at the original government URL, if it is still live.
In rare instances where accessing a live digital version of a resource was not possible (eg: where a government website is no longer accessible) we used the earliest link available in the Wayback archive for that resource. This can reasonably be expected to be the Wayback version that had experienced the least change since the time of its official publication.
BASIC is an independent, non-profit think tank based in the UK. We work to safeguard humanity and Earth’s ecosystem from nuclear risks and interconnected security threats, for generations to come.