These five states are known to have detonated a nuclear explosive before 1 January 1967 and are thus nuclear weapons states under the
Treaty on the Non-Proliferation of Nuclear Weapons. They also happen to be the
UN Security Council's (UNSC)
permanent members with
veto power on UNSC resolutions.
United States " fireball, the first man-made
nuclear explosion, 1945 The United States developed the first nuclear weapons during
World War II in cooperation with the United Kingdom and Canada as part of the
Manhattan Project, out of the apprehension that
Nazi Germany would develop them first. It tested the first nuclear weapon on 16 July 1945 ("
Trinity") at 5:30 am, and remains the only country to have used nuclear weapons in war, having
bombed the Japanese cities of
Hiroshima and
Nagasaki in the closing stages of World War II. The project expenditure through 1 October 1945 was reportedly $1.845–$2billion, in nominal terms, roughly 0.8 percent of the US GDP in 1945 and equivalent to about $billion today. The United States was the first nation to develop the
hydrogen bomb, testing an experimental prototype in 1952 ("
Ivy Mike") and a deployable weapon in 1954 ("
Castle Bravo"). Throughout the
Cold War it continued to modernize and enlarge its nuclear arsenal, but from 1992 on has been involved primarily in a program of
stockpile stewardship. The US nuclear arsenal contained 31,175 warheads at its Cold War height (in 1966). During the Cold War, the United States built more nuclear weapons than all other nations at approximately 70,000 warheads.
Russia (successor to the Soviet Union) The Soviet Union tested its first nuclear weapon ("
RDS-1") in 1949. This crash project was developed partially with information obtained via the
atomic spies at the United States' Manhattan Project during and after World War II. The Soviet Union was the second nation to have developed and tested a nuclear weapon. It tested its first megaton-range hydrogen bomb ("
RDS-37") in 1955. The Soviet Union also tested the most powerful explosive ever detonated by humans, ("
Tsar Bomba"), with a theoretical yield of 100 megatons, reduced to 50 when detonated. After its dissolution in 1991, the Soviet weapons entered officially into the possession of its
successor state, the Russian Federation. The Soviet nuclear arsenal contained some 45,000
warheads at its peak (in 1986), more than any other nation had possessed at any point in history; the Soviet Union built about 55,000 nuclear warheads since 1949. The
British Armed Forces maintained a fleet of
V bomber strategic bombers and
ballistic missile submarines (SSBNs) equipped with nuclear weapons during the Cold War. The
Royal Navy currently maintains a fleet of four ballistic missile submarines equipped with
Trident II missiles. In 2016, the
UK House of Commons voted to renew the British nuclear weapons system with the , without setting a date for the commencement of service of a replacement to the current system. At the
2025 NATO summit, the UK announced it would purchase 12 US-made F-35A jets which are expected to carry US-made atomic bombs—expanding UK nuclear capability to include airborne delivery systems.
France (left) and French nuclear-powered
aircraft carrier Charles de Gaulle (right), each of which carries nuclear-capable
warplanes France tested its first nuclear weapon in 1960 ("
Gerboise Bleue"), based mostly on its own research. It was motivated by the
Suez Crisis diplomatic tension in relation to both the Soviet Union and its allies, the United States and United Kingdom. It was also relevant to retain great power status, alongside the United Kingdom, during the post-colonial Cold War (see:
Force de frappe). France tested its first hydrogen bomb in 1968 ("
Opération Canopus"). After the Cold War, France has disarmed 175 warheads with the reduction and modernization of its arsenal that has now evolved to a dual system based on
submarine-launched ballistic missiles (SLBMs) and medium-range air-to-surface missiles (
Rafale fighter-bombers). However, new nuclear weapons are in development and reformed nuclear squadrons were trained during
Enduring Freedom operations in Afghanistan. France acceded to the Nuclear Non-Proliferation Treaty in 1992. In January 2006, President
Jacques Chirac stated a terrorist act or the use of
weapons of mass destruction against France would result in a nuclear counterattack. In February 2015, President
François Hollande stressed the need for a nuclear deterrent in "a dangerous world". He also detailed the French deterrent as "fewer than 300" nuclear warheads, three sets of 16 submarine-launched ballistic missiles and 54 medium-range air-to-surface missiles and urged other states to show similar transparency.
China China tested its first nuclear weapon device ("
596") in 1964 at the
Lop Nur test site. The weapon was developed as a deterrent against both the United States and the Soviet Union. Two years later, China had a fission bomb capable of being put onto a
nuclear missile. It tested its first hydrogen bomb ("
Test No. 6") in 1967, 32 months after testing its first nuclear weapon (the shortest fission-to-fusion development known in history). China is the only NPT nuclear-weapon state to give an unqualified negative
security assurance with its "
no first use" policy. China acceded to the Nuclear Non-Proliferation Treaty in 1992. As of February 2024, China had an estimated total inventory of approximately 500 warheads. According to
Stockholm International Peace Research Institute (SIPRI), China is in the middle of a significant modernization and expansion of its nuclear arsenal. Its nuclear stockpile is expected to continue growing over the coming decade and some projections suggest that it will deploy at least as many intercontinental ballistic missiles (ICBMs) as either Russia or the US in that period. However, China's overall nuclear warhead stockpile is still expected to remain smaller than that of either of those states. The Yearbook published by SIPRI in 2024 revealed that China's nuclear warheads stockpile increased by 90 in 2023, reaching 500 warheads.
US Department of Defense officials estimate that China had more than 600 operational nuclear warheads as of December 2024, and it was on track to possess 1,000 nuclear weapons by the year 2030. == States declaring possession of nuclear weapons ==