States with Nuclear Weapons

The Nuclear Non-Proliferation Treaty defines a nuclear-weapon state as one that exploded a nuclear weapon or other nuclear explosive device before January 1, 1967.[4] Under that definition, five states qualify: the United States, Russia, the United Kingdom, France, and China.[4] These governments have jointly described themselves as the "Five Nuclear-Weapon States" and reaffirmed their NPT obligations, including the principle that "a nuclear war cannot be won and must never be fought."[3]

All other NPT states-parties are classified under the treaty as nonnuclear-weapon states.[4] This legal distinction determines the obligations attached to each category and means that the treaty's formal roster has remained fixed at five even as additional countries developed nuclear arms.

The first nuclear capabilities emerged during or shortly after World War II.[5] By 1954, the United States, the Soviet Union, and Britain had each conducted nuclear tests and held operational, deliverable stockpiles.[6] A document from that year estimated that the American stockpile numbered in four figures, the Soviet stockpile in three figures, and the British stockpile in two figures, illustrating the early disparity among the three programs.[6]

France exploded its first nuclear bomb in 1960, and China achieved nuclear capability in 1964, bringing the number of nuclear powers to five by that year.[5] Concern that nuclear technology could spread more widely helped drive negotiations over the NPT, which entered into force in 1970 with the goal of limiting further proliferation.[5]

Several countries later reversed course. Argentina, Brazil, and South Africa abandoned nuclear-weapons programs and joined the NPT as nonnuclear-weapon states in the 1990s.[4] Ukraine, Belarus, and Kazakhstan, which had inherited former Soviet weapons on their territories, relinquished them and joined the NPT as nonnuclear-weapon states during the same decade.[4]

India, Pakistan, and Israel have never signed the NPT. A Congressional Research Service report lists the three as possessing nuclear weapons while noting separately that Israel is generally thought to possess them and maintains a policy of ambiguity.[4] A Jerusalem Center for Public Affairs analysis described India and Pakistan as becoming de facto nuclear powers after their May 1998 tests, increasing the practical count from five to seven at that time.[7] Both countries have continued expanding their arsenals and developing new types of nuclear delivery systems.[2]

North Korea signed the NPT but announced its withdrawal in 2003. The Congressional Research Service says it possesses a small number of nuclear weapons, while noting that whether it legally remains an NPT state-party is unclear.[4] In 2009, North Korea announced a successful underground nuclear test. The event apparently produced an earth tremor measuring 4.7 on the Richter scale, according to the U.S. Geological Survey; a U.S. State Department official said the department was aware of reports of the test.[8] North Korea has continued to prioritize its military nuclear program as a central element of its national security strategy.[2]

The United States and Russia dominate the global nuclear inventory. SIPRI reported in 2022 that the two countries together possessed more than 90 percent of all nuclear weapons.[2] A 2025 Congressional Record statement cited approximately 13,400 nuclear weapons worldwide, with roughly 90 percent held in the two countries' arsenals.[9]

The scale of the American arsenal has changed dramatically. The United States held a peak of 31,255 warheads in 1967, a figure that had fallen to 5,113 by 2010.[10] The decline illustrates the scale of reductions from the Cold War peak, although the United States and the other nuclear-armed states have continued to modernize or upgrade their remaining forces.[2]

SIPRI's 2022 Yearbook identified the same nine nuclear-armed states, while its 2023 assessment estimated a total inventory of 12,512 warheads, including 9,576 in military stockpiles and 3,844 of those deployed.[2][1] SIPRI expected nuclear arsenals to grow over the following decade. It reported that all nine states were increasing or upgrading their arsenals and that most were sharpening nuclear rhetoric and expanding the role of nuclear weapons in their military strategies.[2]

Israel occupies a distinctive position among the nine states in SIPRI's count because it does not publicly acknowledge possessing nuclear weapons.[1] A Jerusalem Center for Public Affairs analysis says that, unlike the other eight states, Israel has never tested a weapon or declared itself a nuclear power.[11] Israel is not a party to the NPT.[12][13] The same analysis traces development of an Israeli nuclear deterrent to the period after the War of Independence and says the Dimona reactor was built with French cooperation in the late 1950s.[11]

This posture is known as nuclear ambiguity — a policy of neither confirming nor denying the existence of an arsenal. The Jerusalem Center analysis describes the policy as dating to the 1960s and reports that a 1969 understanding required Israel not to declare or test a weapon.[11] The Congressional Research Service states that Israel is "generally thought to possess nuclear weapons" while maintaining ambiguity.[4] The Times of Israel, citing SIPRI, reported an estimate of approximately 90 Israeli warheads at the beginning of 2023 and noted significant uncertainty because of Israel's opacity.[14]

Israel's inclusion in international tallies therefore rests on external assessment rather than an official Israeli declaration.[1][12] Israel has never officially acknowledged having atomic bombs.[13]

International efforts have focused on preventing Iran from becoming nuclear armed. Pew Research Center identified the United States, Britain, France, Germany, Russia, and China as the E3+3 countries that negotiated with Iran to keep Tehran from crossing a threshold at which it could quickly produce a nuclear bomb.[15] An Anti-Defamation League fact sheet characterized Iran as pursuing nuclear-weapons capability rather than already possessing a confirmed arsenal.[16]

The history of countries that abandoned nuclear programs demonstrates that proliferation is not necessarily irreversible. Argentina, Brazil, and South Africa reversed their programs, while Ukraine, Belarus, and Kazakhstan relinquished former Soviet weapons on their territories.[4] All six joined the NPT as nonnuclear-weapon states in the 1990s.[4]

The terms "nuclear-armed state," "nuclear power," and "NPT-recognized nuclear-weapon state" are not interchangeable. The NPT's legal category of five recognized nuclear-weapon states is narrower than the practical list of nine states assessed to possess weapons.[4][1] The five hold treaty status under a definition based on testing before January 1, 1967; the additional four are included in broader counts because of testing records and acknowledged or assessed possession, not NPT recognition.[4]

Reported totals also depend on the date and categories being counted. SIPRI's January 2023 total inventory of 12,512 warheads included 9,576 in military stockpiles for potential use, of which 3,844 were deployed.[1] A 2025 Congressional Record statement instead cited approximately 13,400 worldwide.[9] Figures from different dates and sources should not be treated as directly interchangeable without attention to their methodology. For states that do not disclose their arsenals, including Israel, estimates remain informed approximations rather than verified inventories.[14]