Nuclear weapons of the United States in the context of "Hydrogen bomb"

A thermonuclear weapon, fusion weapon or hydrogen bomb (H-bomb) is a second-generation nuclear weapon, utilizing nuclear fusion. The most destructive weapons ever created, their yields typically exceed first-generation nuclear weapons by twenty times, with far lower mass and volume requirements. Characteristics of fusion reactions can make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material. Its multi-stage design is distinct from the usage of fusion in simpler boosted fission weapons. The first full-scale thermonuclear test (Ivy Mike) was carried out by the United States in 1952, and the concept has since been employed by at least the five NPT-recognized nuclear-weapon states: the United States, Russia, the United Kingdom, China, and France.

The design of all thermonuclear weapons is believed to be the Teller–Ulam configuration. This relies on radiation implosion, in which X-rays from detonation of the primary stage, a fission bomb, are channelled to compress a separate fusion secondary stage containing thermonuclear fuel, primarily lithium-6 deuteride. During detonation, neutrons convert lithium-6 to helium-4 plus tritium. The heavy isotopes of hydrogen, deuterium and tritium, then undergo a reaction that releases energy and neutrons. For this reason, thermonuclear weapons are often colloquially called hydrogen bombs or H-bombs.

An intercontinental ballistic missile (ICBM) is a ballistic missile with a range greater than 5,500 kilometres (3,400 mi), primarily designed for nuclear weapons delivery (delivering one or more thermonuclear warheads). Conventional, chemical, and biological weapons can also be delivered with varying effectiveness but have never been deployed on ICBMs. Most modern designs support multiple independently targetable reentry vehicles (MIRVs), allowing a single missile to carry several warheads, each of which can strike a different target. The United States, Russia, China, France, India, the United Kingdom, Israel, and North Korea are the only countries known to have operational ICBMs. Pakistan is the only nuclear-armed state that does not possess ICBMs.

Early ICBMs had limited precision, which made them suitable for use only against the largest targets, such as cities. They were seen as a "safe" basing option, one that would keep the deterrent force close to home where it would be difficult to attack. Attacks against military targets (especially hardened ones) demanded the use of a more precise, crewed bomber. Second- and third-generation designs (such as the LGM-118 Peacekeeper) dramatically improved accuracy to the point where even the smallest point targets can be successfully attacked.

The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and energy production, the research and development of nuclear power, the military's nuclear weapons program, nuclear reactor production for the United States Navy, energy-related research, and energy conservation.

The DOE was created in 1977 in the aftermath of the 1973 oil crisis. It sponsors more physical science research than any other U.S. federal agency, the majority of which is conducted through its system of National Laboratories. The DOE also directs research in genomics, with the Human Genome Project originating from a DOE initiative.

The Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT, is an international treaty, the objective of which is to prevent the spread of nuclear weapons and weapons technology, to promote cooperation in the peaceful uses of nuclear energy, and to further the goal of achieving nuclear disarmament and general and complete disarmament. Between 1965 and 1968, the treaty was negotiated by the Eighteen Nation Committee on Disarmament, a United Nations-sponsored organization based in Geneva, Switzerland.

Opened for signature in 1968, the treaty entered into force in 1970. As required by the text, after twenty-five years, NPT parties met in May 1995 and agreed to extend the treaty indefinitely. The treaty defines nuclear-weapon states as those that have built and tested a nuclear explosive device before 1967; these are the United States (1945), Russia (1949), the United Kingdom (1952), France (1960), and China (1964).

There are currently nine sovereign states that are generally understood to possess nuclear weapons, though only eight formally acknowledge possessing them. In order of first successful nuclear test, the world's nine nuclear-armed states are the United States (1945), Russia (1949), the United Kingdom (1952), France (1960), China (1964), India (1974), Pakistan (1998), and North Korea (2006); Israel is believed to have acquired nuclear weapons around 1967, but has never openly tested or formally acknowledged having them. Under the Non-Proliferation Treaty (NPT), the United States, Russia, the United Kingdom, France, and China are recognized "nuclear-weapons states" (NWS). They are also the five permanent members of the United Nations Security Council. Israel, India, and Pakistan never signed the NPT, while North Korea acceded to it in 1985 before announcing withdrawal in 2003.

South Africa developed nuclear weapons by 1982 but dismantled them around 1989 and joined the NPT in 1991. Following the dissolution of the Soviet Union in 1991, the former Soviet republics of Ukraine, Kazakhstan, and Belarus had nuclear weapons deployed on their territories, but agreed to transfer them to Russia (which inherited the Soviet Union's international rights and obligations) and join the NPT as non-nuclear-weapon states.

In 1952, the United Kingdom became the third country (after the United States and the Soviet Union) to develop and test nuclear weapons, and is one of the five nuclear-weapon states under the Treaty on the Non-Proliferation of Nuclear Weapons. As of 2025, the UK possesses a stockpile of approximately 225 warheads, with 120 deployed on its only delivery system, the Trident programme's submarine-launched ballistic missiles. Additionally, United States B61 nuclear bombs have been stored at RAF Lakenheath since 2025. In 2025, the UK announced plans to procure 12 F-35A aircraft capable of delivering B61s.

Since 1969, the Royal Navy has operated the continuous at-sea deterrent, with at least one ballistic missile submarine always on patrol. Under the Polaris Sales Agreement, the US supplied the UK with Polaris missiles and nuclear submarine technology, in exchange for the general commitment of these forces to NATO. In 1982, an amendment allowed the purchase of Trident II missiles, and since 1998, Trident has been the only nuclear weapons system in British service. Four Vanguard-class submarines are based at HMNB Clyde in Scotland. Each is armed with up to sixteen Trident II missiles, each carrying warheads in up to eight multiple independently targetable re-entry vehicles (MIRVs).

China was the fifth country to develop and test nuclear weapons. China's tested its first nuclear weapon in 1964 and its first full-scale thermonuclear weapon in 1967. It is one of the five nuclear-weapon states recognized by the Nuclear Non-Proliferation Treaty (NPT), to which it acceded in 1992. It carried out 45 nuclear tests before signing the Comprehensive Nuclear-Test-Ban Treaty in 1996.

The Federation of American Scientists and the Stockholm International Peace Research Institute estimate China's stockpile at approximately 600 nuclear warheads as of 2025, making it the third-largest in the world. It is the only NPT nuclear-weapon state significantly expanding its arsenal, which has doubled since 2019, and is projected to reach between 750 and 1,500 warheads by 2035, although it has not restarted fissile material production. Unlike the US and Russia, nearly all Chinese warheads are believed to be in central storage, separate from their delivery system.

The Force de dissuasion (French pronunciation: [fɔʁs də disɥazjɔ̃]; English: 'Deterrence Force'), known as the Force de frappe ([fɔʁs də fʁɑp]; 'Strike Force') prior to 1961, is the French nuclear deterrence force. The Force de dissuasion used to be a triad of air-, sea- and land-based nuclear weapons intended for deterrence. With the end of the Cold War, France decommissioned all its land-based nuclear missiles. The Force de dissuasion today is only an air- and sea-based arsenal. The French Nuclear Force, part of the French military, is the fourth largest nuclear-weapons force in the world, after the nuclear triads of the United States, the Russian Federation, and the People's Republic of China.

France's programme was shaped not only by the Cold War, but by the trauma that resulted from the Battle of France. General Pierre Marie Gallois, one of the architects of the deterrence force, is said to have been marked "by the tragic effects of an excess of German power" in his strategic thinking. France developed a military nuclear programme with the aim of retaining a strategic advantage over Germany. In 1961 Charles de Gaulle reminded John F. Kennedy that "Germany is legally prevented from having any [nuclear weapons]," adding that "the disadvantages deriving from German possession of atomic weapons would be far greater than the advantages."