Stockpile Stewardship & Sustainment

1938 · 88 years ago

Nuclear fission was discovered in Berlin, showing that splitting an atom could release enormous energy

Otto Hahn and Fritz Strassmann's experiment, interpreted by Lise Meitner and Otto Frisch, demonstrated that uranium nuclei could split and release energy, the scientific finding that made an industrial-scale weapons programme conceivable within a few years.

1939–45 · 87 years ago

The United States, United Kingdom and Canada developed the first nuclear weapons through the Manhattan Project

The first nuclear weapons were produced during the Second World War by a US-led collaboration with Britain and Canada. Production required a large scientific-industrial complex, chiefly for fissile material via reactors and reprocessing plants for plutonium or uranium enrichment facilities, establishing the template for every subsequent weapons industrial base.

1940s · 86 years ago

The United States and the Soviet Union failed to reach early arms control agreements amid mutual distrust

In the late 1940s a lack of mutual trust blocked progress on controlling nuclear weapons. The failure entrenched parallel national weapons industrial bases and set the conditions for the Cold War arms race.

1940–96 · 86 years ago

The Brookings Institution audited US spending of $11.9 trillion on nuclear weapons

The audit found that 57 per cent of the total went on delivery systems, 7 per cent ($820 billion) on making the weapons themselves and 6.3 per cent ($749 billion) on environmental remediation and waste management such as cleaning up the Hanford site. The breakdown quantifies the true cost structure of sustaining a weapons industrial base.

1943 · 83 years ago

The Manhattan Project established the production complex at Oak Ridge and Hanford

Massive industrial sites built to enrich uranium and produce plutonium at scale gave the United States the material for its first weapons and set the template of dedicated, secret production infrastructure that other nuclear programmes later followed.

1945 · 81 years ago

The United States Army Air Forces detonated Little Boy and Fat Man over Hiroshima and Nagasaki

A uranium gun-type bomb was dropped on Hiroshima on 6 August 1945 and a plutonium implosion bomb on Nagasaki on 9 August. The bombings killed roughly 150,000 to 246,000 people and remain the only wartime use of nuclear weapons, demonstrating that both principal fissile-material production routes had reached weapons maturity.

1945 · 81 years ago

Harry Daghlian received a lethal dose of radiation in a criticality accident at Los Alamos

On 21 August 1945 a physicist working on a plutonium-gallium core at Los Alamos National Laboratory caused it to enter prompt criticality. He died 25 days later of radiation poisoning, one of the earliest fatalities in the weapons production complex.

1946 · 80 years ago

The United States placed its nuclear weapons complex under civilian control

The Atomic Energy Act transferred authority over weapons production from the wartime military project to a new civilian Atomic Energy Commission, establishing a legal and institutional model for governing the industrial base that other nuclear states later adapted.

1946 · 80 years ago

Louis Slotin caused the same core to go briefly supercritical at Los Alamos

On 21 May 1946 a further experiment on the plutonium core produced a supercritical excursion, exposing the physicist to a lethal dose of gamma and neutron radiation. He died nine days later, prompting lasting attention to safety practice in weapons laboratories.

1948 · 78 years ago

The Soviet Union brought its first plutonium production reactor online at Mayak

The reactor at what became the closed city of Chelyabinsk-40 produced the plutonium used in the Soviet Union's first atomic bomb the following year, founding the industrial base that sustained the Soviet, and later Russian, arsenal.

early 1950s · 76 years ago

The Livermore Laboratory planned the gigaton-class Gnomon and Sundial test devices

In the early 1950s the US laboratory drew up plans to test bombs of 1 gigaton and 10 gigatons of TNT equivalent. The designs were never built but illustrate the extreme yields the American weapons design establishment considered feasible.

1950s · 76 years ago

The USSR fielded the first partially thermonuclear weapons using external boosting

External boosting allowed Soviet designers to deploy partially thermonuclear devices during the 1950s arms race, when bombers were the only delivery vehicle. The method later became obsolete because it required a spherical bomb geometry unsuited to missiles.

1954 · 72 years ago

Japanese peace movements converged to form the Japan Council against Atomic and Hydrogen Bombs

In 1954 Japanese anti-nuclear groups united into a single national council. An estimated 35 million signatures were gathered on petitions calling for bans on nuclear weapons, creating sustained public pressure against Pacific testing.

1954 · 72 years ago

The Castle Bravo test first brought radioactive fallout to global public attention

The hydrogen bomb test at the Pacific Proving Grounds contaminated the crew and catch of the Japanese fishing boat Lucky Dragon. The incident made fallout from atmospheric testing an international political issue and fed pressure toward test limitation.

1955 · 71 years ago

Bertrand Russell and Albert Einstein issued the Russell–Einstein Manifesto in London

Issued on 9 July 1955 and signed by eleven eminent intellectuals and scientists, the manifesto warned of nuclear dangers at the height of the Cold War. Einstein signed days before his death, and the appeal led directly to the Pugwash movement.

1957 · 69 years ago

The Kyshtym disaster contaminated a wide area around the Mayak plutonium complex

A storage tank explosion at the Soviet Union's main plutonium production and reprocessing site released large quantities of radioactive material, one of the worst nuclear accidents on record and a demonstration of the risks inherent in the weapons industrial base.

1957 · 69 years ago

The International Atomic Energy Agency was established under a United Nations mandate

The IAEA was created to encourage peaceful applications of nuclear technology, provide international safeguards against misuse and promote safety measures. It became the principal body policing the boundary between civil nuclear industry and weapons production.

1957 · 69 years ago

The Pugwash Conferences on Science and World Affairs held their first conference on nuclear dangers

Following the Russell–Einstein Manifesto, the inaugural Pugwash conference took place in July 1957. It established a durable transnational scientists' channel on arms control and disarmament.

1958 · 68 years ago

The Campaign for Nuclear Disarmament organised the first Aldermaston March

At Easter 1958 several thousand people marched for four days from Trafalgar Square to the Atomic Weapons Research Establishment at Aldermaston. The marches continued into the late 1960s with tens of thousands taking part, targeting Britain's weapons industrial base directly.

1959 · 67 years ago

The Bulletin of the Atomic Scientists launched a campaign against ocean dumping of radioactive waste

A 1959 letter in the Bulletin began a successful campaign to stop the Atomic Energy Commission dumping radioactive waste in the sea 19 kilometres from Boston. It marked early public constraint on the waste-handling side of the weapons complex.

1962 · 64 years ago

The Starfish Prime test revealed the nuclear electromagnetic pulse effect

During the 1962 high-altitude nuclear test an unexpected effect was produced, later termed the nuclear electromagnetic pulse. The discovery reshaped understanding of weapons effects and hardening requirements for military and civil systems.

1962 · 64 years ago

Linus Pauling won the Nobel Peace Prize for opposing atmospheric testing

Pauling was awarded the prize for his work to stop atmospheric nuclear testing. The award helped spread the 'Ban the Bomb' movement internationally.

1963 · 63 years ago

The Partial Test Ban Treaty ended atmospheric, underwater and space nuclear testing

Signed by the United States, the Soviet Union and the United Kingdom after growing public alarm over radioactive fallout, the treaty pushed all subsequent weapons testing underground and reshaped the infrastructure each programme needed.

1964 · 62 years ago

African states agreed the Treaty of Pelindaba nuclear-weapon-free zone

The treaty prohibits nuclear weapons in many African countries. It formed part of the emerging regional architecture excluding weapons production and deployment from whole continents.

1967 · 59 years ago

Latin American and Caribbean states signed the Treaty of Tlatelolco

The 1967 treaty prohibited any production or deployment of nuclear weapons in Latin America and the Caribbean. It was the first regional nuclear-weapon-free zone covering populated territory.

1967 · 59 years ago

The international community adopted the Outer Space Treaty barring nuclear weapons in orbit

The 1967 treaty prohibits placing nuclear weapons in orbit. Reports in 2024 that Russia planned orbital nuclear weapons were framed as a breach of this instrument.

1968 · 58 years ago

Signatory states concluded the Treaty on the Non-Proliferation of Nuclear Weapons

The NPT restricted the activities signatories could undertake, allowing transfer of non-military nuclear technology without fear of proliferation. It also obliges all signatories to pursue negotiations in good faith towards complete disarmament, becoming the central legal framework separating civil and military nuclear industry.

1976 · 50 years ago

The United States and the Soviet Union agreed the Peaceful Nuclear Explosions Treaty

After both powers conducted numerous peaceful nuclear explosions during the 1960s and 1970s, the 1976 treaty defined and limited such uses. It closed a loophole by which weapons-scale devices could be detonated under a civil rationale.

1980s · 46 years ago

The US Army procured neutron warheads for tactical artillery and missiles

Enhanced-radiation warheads were procured in the 1980s for 200 mm W79 and 155 mm W82 artillery shells and short-range missile forces, exploiting high energy neutrons' ability to penetrate tank armour. They were not deployed in Europe.

1980 · 46 years ago

The United States suffered the Damascus Accident Titan missile explosion

On 18–19 September 1980 a Titan missile armed with a nuclear warhead exploded in its silo at Damascus, Arkansas. It was among the most serious of a long series of US nuclear weapons accidents affecting confidence in stockpile safety.

February 2026 · 6 months ago

The National Nuclear Security Administration sought more funding for plutonium pit production

The budget request for the agency's weapons activities account sought increased funding for the Savannah River and Los Alamos pit facilities and for warhead life-extension work, continuing a pattern of rising costs across the modernisation portfolio.

• Independent oversight bodies repeated earlier warnings about schedule risk

Early 2026 · this year

The Non-Proliferation Treaty review process moved towards a 2026 review conference

Preparatory sessions in the two years before the conference exposed continued disagreement between nuclear-armed and non-nuclear states over the pace of disarmament and the transparency of fissile material stocks retained for weapons programmes.

• Non-nuclear-weapon states pressed for faster disarmament steps

2025 · 1 year ago

Donald Trump called for renewed nuclear weapons testing

On 30 October 2025 the US President urged a resumption of nuclear testing to keep pace with Russia and China. He did not clarify whether he meant nuclear explosive testing or testing of delivery systems.

2025 · last year

The United States kept using its inertial confinement fusion facility for stockpile science

The National Ignition Facility in California continued a programme of experiments that feed data on warhead physics into simulations, part of the science-based approach that has underpinned the US moratorium on explosive nuclear testing since the early 1990s.

2025 · last year

Russia continued investing in its closed nuclear weapons cities

State statements pointed to continued modernisation of design and production facilities at closed cities such as Sarov, part of a long-running effort to renew Soviet-era infrastructure, though independent verification of specific projects remains limited.

2025 · last year

Pakistan continued operating its Khushab plutonium production reactor complex

Four reactors at the site remain central to Pakistan's fissile material stock, operating alongside enrichment capacity at Kahuta. Outside estimates suggest the programme continues to expand at a measured, steady pace rather than any sudden acceleration.

2025 · last year

North Korea continued building an experimental light-water reactor at Yongbyon

Satellite imagery tracked by independent researchers showed continued work on the reactor, which analysts believe could eventually add plutonium or tritium production capacity to North Korea's existing gas-graphite reactor and enrichment facilities at the same site.

2025 · last year

France and the United Kingdom expanded joint hydrodynamic testing under a shared facility

Work continued at the Epure facility at Valduc, built under a bilateral treaty, letting both countries study warhead physics through hydrodynamic experiments without a return to explosive testing, a capability each also maintains at national laboratories.

2025 · last year

China expanded fast reactor construction that analysts link to weapons-usable plutonium

Additional reactor units progressed at the Xiapu site, officially described as civilian breeder reactor development. Western analysts noted the technology can also produce plutonium of a grade usable in warheads, alongside China's separately growing uranium enrichment capacity.

2025 · last year

The United States pushed back the completion date for the Uranium Processing Facility

The Y-12 facility in Oak Ridge, Tennessee, intended to replace Cold War-era buildings that handle weapons-grade uranium, saw its schedule and cost estimate revised again, extending a pattern of delay that has run for more than a decade.

September 2024 · 2 years ago

North Korea revealed a uranium enrichment facility to the public for the first time

State media released images of Kim Jong Un touring a hall of centrifuge cascades, the first official confirmation of the layout of a North Korean enrichment site, though the facility's precise location was not disclosed.

• Outside analysts could not independently confirm the site's location

2020s · 6 years ago

China began significantly expanding its nuclear arsenal

China is expanding its stockpile, with projections of more than 1,000 warheads by 2030 and up to 1,500 by 2035. The build-up implies a substantial scaling of its weapons production industrial base.

2019 · 7 years ago

The US Joint Chiefs of Staff published the Doctrine for Joint Nuclear Operations

The June 2019 publication stated that integration of nuclear weapons employment with conventional and special operations forces is essential to mission success. It signalled a doctrinal reintegration of nuclear and conventional planning.

2017 · 9 years ago

122 countries voted to adopt the Treaty on the Prohibition of Nuclear Weapons

Mainly Global South states adopted the prohibition treaty in 2017, and it entered into force in 2021. It created the first comprehensive legal ban on nuclear weapons, though without the participation of the armed states.

2010 · 16 years ago

The United States and Russia signed an agreement to dispose of excess weapons plutonium

The Plutonium Management and Disposition Agreement committed each side to eliminate 34 tonnes of weapons-grade plutonium, enough for thousands of warheads. The United States later suspended its involvement, and disposal of the material remains largely incomplete.

2009 · 17 years ago

Barack Obama advocated a world without nuclear weapons in Prague

In an April 2009 speech the US President set out the goal of eventual nuclear abolition. The address gave renewed political momentum to disarmament campaigns such as Global Zero after the Cold War.

2006 · 20 years ago

Former Soviet republics of Central Asia established a Central Asian Nuclear Weapon Free Zone

In 2006 the Central Asian states agreed a zone prohibiting nuclear weapons across their territories. It extended the nuclear-weapon-free zone model into the post-Soviet space.

2003 · 23 years ago

The United States invaded Iraq citing alleged pursuit of nuclear arms

One stated casus belli for the 2003 war was the accusation that Iraq was actively pursuing nuclear weapons. The programme was soon found to have been discontinued.

1998 · 28 years ago

The United Nations established the Office for Disarmament Affairs

UNODA was created in January 1998 as part of Secretary-General Kofi Annan's UN reform plan presented to the General Assembly in July 1997. It became the Secretariat's institutional home for disarmament work.

1998 · 28 years ago

The United States Department of Energy disclosed abandoned investment in pure fusion weapons

The DOE revealed in 1998 that the US had made a substantial past investment in developing pure fusion weapons but that no credible design had resulted. It stated that the US neither possessed nor was developing such a weapon.

1998 · 28 years ago

India and Pakistan conducted nuclear tests and drew economic sanctions

Both states, neither a signatory to the Non-Proliferation Treaty, tested nuclear weapons in 1998. Temporary economic sanctions were levied against them, demonstrating the limits of the non-proliferation regime over non-parties.

1996 · 30 years ago

The International Court of Justice issued an advisory opinion on the legality of nuclear weapons

The UN's highest court held in 1996 that use or threat of use would generally be contrary to international law applicable in armed conflict. It declined to rule on extreme circumstances where the survival of a state was at stake.

1996 · 30 years ago

The Comprehensive Nuclear-Test-Ban Treaty opened for signature

The Comprehensive Nuclear-Test-Ban Treaty opened for signature in 1996, prohibiting all nuclear weapons testing anywhere, including explosions for peaceful purposes, and backed by an international monitoring network built to detect violations. Entry into force requires ratification by 44 specified states; as of 2012 eight of these, including the United States, had still not ratified, leaving the treaty stalled.

1992 · 34 years ago

The United States halted underground nuclear testing

A moratorium beginning that September ended decades of American nuclear explosive tests and shifted the weapons complex towards a science-based stewardship approach, relying on simulation and laboratory experiments to certify the stockpile without detonations.

1991 · 35 years ago

The United States and the Soviet Union announced the Presidential Nuclear Initiatives

The 1991 non-binding initiatives sat alongside binding treaties such as START I, INF and later New START in reducing arsenals. They accelerated the withdrawal of tactical weapons after the Cold War.

1990 · 36 years ago

The United States Congress passed the Radiation Exposure Compensation Act

The 1990 Act created the only national scheme compensating nuclear test victims, with more than $1.38 billion approved by March 2009. It represented an acknowledgement of the human costs generated by the testing and production complex.

1989 · 37 years ago

Rocky Flats was raided and shut down over safety violations

An FBI and Environmental Protection Agency raid on the plant near Denver, the sole American source of plutonium warhead cores, exposed serious safety and environmental failures and closed the facility, leaving the country without pit production for decades.

1986 · 40 years ago

Mikhail Gorbachev proposed a three-stage programme to abolish nuclear weapons

In January 1986 the Soviet leader publicly called for the elimination of the world's nuclear weapons by the end of the twentieth century. The proposal reframed superpower diplomacy towards deep reductions.

1986 · 40 years ago

The global nuclear stockpile peaked at more than 64,000 weapons

The worldwide inventory reached its maximum in 1986 before decades of reductions brought it to around 9,600 by 2025. The peak marks the high-water mark of Cold War weapons production capacity.

1981 · 45 years ago

Israel bombed the Osirak reactor under construction in Iraq

Israel struck the Iraqi reactor in what it described as an effort to halt Iraq's nuclear weapons ambitions. The attack established a precedent for preventive strikes against nuclear industrial infrastructure, repeated against a Syrian reactor in 2007.