Soviet atomic bomb project in the context of Atomic spies

The nuclear arms race was an arms race competition for supremacy in nuclear warfare between the United States, the Soviet Union, and their respective allies during the Cold War. During this same period, in addition to the American and Soviet nuclear stockpiles, other countries developed nuclear weapons, though no other country engaged in warhead production on nearly the same scale as the two superpowers.

The race began during World War II, dominated by the Western Allies' Manhattan Project and Soviet atomic spies. Following the atomic bombings of Hiroshima and Nagasaki, the Soviet Union accelerated its atomic bomb project, resulting in the RDS-1 test in 1949. Both sides then pursued an all-out effort, realizing deployable thermonuclear weapons by the mid-1950s. The arms race in nuclear testing culminated with the 1961 Tsar Bomba. Atmospheric testing was ended in the 1963 Partial Nuclear Test Ban Treaty. Subsequent work focused on the miniaturization of warheads at LLNL and VNIITF, and the neutron bomb.

Nuclear proliferation is the spread of nuclear weapons to additional countries, particularly those not recognized as nuclear-weapon states by the Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT. Nuclear proliferation occurs through the spread of fissile material, and the technology and capabilities needed to produce it and to design and manufacture nuclear weapons. In a modern context, it also includes the spread of nuclear weapons to non-state actors. Proliferation has been opposed by many nations with and without nuclear weapons, as governments fear that more countries with nuclear weapons will increase the possibility of nuclear warfare (including the so-called countervalue targeting of civilians), de-stabilize international relations, or infringe upon the principle of state sovereignty. Conversely, supporters of deterrence theory argue that controlled proliferation decreases conflict rates via nuclear peace.

Nuclear weapons were initially researched during World War II, jointly by the United States, United Kingdom and Canada, and separately by Germany, Japan, the Soviet Union, and France. The United States was the first and is the only country to have used a nuclear weapon in war, when it used two bombs against Japan in August 1945. After surrendering, Germany and Japan ceased to be involved in any nuclear weapon research. A nuclear arms race followed, with further countries developing and testing nuclear weapons. The US primarily competed with the Soviet Union, which carried out their first test in 1949. Seven other countries developed nuclear weapons during the Cold War. The UK and France, both NATO members, developed fission and fusion weapons throughout the 1950s, and 1960s, respectively. China developed both against the backdrop of the Sino-Soviet split.

Andrei Dmitrievich Sakharov (Russian: Андрей Дмитриевич Сахаров; 21 May 1921 – 14 December 1989) was a Soviet physicist and a Nobel Peace Prize laureate, which he was awarded in 1975 for emphasizing human rights around the world.

Although he spent his career in physics in the Soviet program of nuclear weapons, overseeing the development of thermonuclear weapons, Sakharov also did fundamental work in understanding particle physics, magnetism, and physical cosmology. Sakharov is mostly known for his political activism for individual freedom, human rights, civil liberties and reforms in the Soviet Union, for which he was deemed a dissident and faced persecution from the Soviet establishment.

Manfred Baron von Ardenne (German pronunciation: [ˈmanfʁeːt fɔn aʁˈdɛn]; 20 January 1907 – 26 May 1997) was a German researcher, autodidact in applied physics, and an inventor. He took out approximately 600 patents in fields including electron microscopy, medical technology, nuclear technology, plasma physics, and radio and television technology. From 1928 to 1945, he directed his self-funded and private research laboratory Forschungslaboratorium für Elektronenphysik, where he developed and invented many techniques used in modern physics.

After World War II, von Ardenne was held in Soviet custody and was one of many of the German nuclear physicists in the Soviet program of nuclear weapons, and later honored with the Stalin Prize.

Building on major scientific breakthroughs made during the 1930s, the United Kingdom began the world's first nuclear weapons research project, codenamed Tube Alloys, in 1941, during World War II. The United States, in collaboration with the United Kingdom, initiated the Manhattan Project the following year to build a weapon using nuclear fission. The project also involved Canada. In August 1945, the atomic bombings of Hiroshima and Nagasaki were conducted by the United States, with British consent, against Japan at the close of that war, standing to date as the only use of nuclear weapons in hostilities.

The Soviet Union started development shortly after with their own atomic bomb project, and not long after, both countries were developing even more powerful fusion weapons known as hydrogen bombs. Britain and France built their own systems in the 1950s, and the number of states with nuclear capabilities has gradually grown larger in the decades since.

The United Armed Forces of the Commonwealth of Independent States (Russian: Объединённые Вооружённые силы Содружества Независимых Государств) was a short-lived military entity associated with the Commonwealth of Independent States. It was created in 1992 after the demise of the Soviet Union, and was intended to be the continuation of the Soviet Armed Forces and to hold control over the Soviet Union's nuclear weapons.

It was rapidly superseded by the de facto Russian control of those nuclear weapons, and the formation of separate national armies for each of the former Soviet states, and had effectively ceased to exist by the end of 1993.

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).

Viktor Borisovich Adamsky (Russian: Ви́ктор Бори́сович Ада́мский; 30 April 1923 – 14 December 2005) was a Soviet and Russian physicist known for his work on the former Soviet program of nuclear weapons.

Yuri Nikolayevich Babayev (Russian: Юрий Николаевич Бабаев; 21 May 1928 – 6 October 1986), k.N, was a Soviet physicist who spent a long career in the former Soviet program of nuclear weapons, and known as one of the principles who designed the Tsar Bomba, the largest-ever nuclear weapon.

Yuri Alexeyevich Trutnev (Russian: Юрий Алексеевич Трутнев; 2 November 1927 – 6 August 2021) was a Russian physicist and a professor of engineering at the National Research Nuclear University MEPhI (Moscow Engineering Physics Institute).

His career in physics spent in the former Soviet program of development of nuclear weapons and was one the designers in the RDS-37 (the Soviet Union's first two-stage thermonuclear device), and the RDS-220 (the largest-ever-yield nuclear device) and many other nuclear charges.

Yakov Borisovich Zeldovich ForMemRS (Russian: Я́ков Бори́сович Зельдо́вич, Belarusian: Я́каў Бары́савіч Зяльдо́віч; 8 March 1914 – 2 December 1987), also known as YaB, D.S. was a leading Soviet physicist of Belarusian origin, who is known for his prolific contributions in physical cosmology, physics of thermonuclear reactions, combustion, and hydrodynamical phenomena.

From 1943, Zeldovich, a self-taught physicist, started his career by playing a crucial role in the development of the former Soviet program of nuclear weapons. In 1963, he returned to academia to embark on pioneering contributions on the fundamental understanding of the thermodynamics of black holes and expanding the scope of physical cosmology.

Georgy Flerov, also spelled Flyorov (Russian: Гео́ргий Никола́евич Флёров, romanized: Georgii Nikolayevich Flërov, IPA: [ɡʲɪˈorɡʲɪj nʲɪkɐˈlajɪvʲɪtɕ ˈflʲɵrəf]; 2 March 1913 – 19 November 1990), was a Soviet physicist who is known for his discovery of spontaneous fission and his important contribution towards crystallography and material science, for which, he was honored with many awards. In addition, he is also known for his letter directed to Joseph Stalin, during the midst of World War II, to start a program of nuclear weapons in the Soviet Union.

In 2012, element 114 was named flerovium after the research laboratory at the Joint Institute for Nuclear Research bearing his name.

The Mayak Production Association (Russian: Производственное объединение «Маяк», Proizvodstvennoye ob′yedineniye "Mayak", from Маяк 'lighthouse') is one of the largest nuclear facilities in the Russian Federation, housing production reactors (non electricity) and a reprocessing plant. The closest settlements are Ozyorsk to the northwest and Novogornyi to the south.

Lavrentiy Beria led the Soviet atomic bomb project. He directed the construction of the Mayak plutonium plant in the Southern Urals between 1945 and 1948, in a great hurry and secrecy as part of the Soviet Union's atomic bomb project. The plant had a similar purpose to the Hanford Site of the Manhattan Project. Over 40,000 gulag prisoners and POWs built the factory and the closed nuclear city of Ozyorsk, called at the time by its classified postal code "Chelyabinsk-40". The first reactor, A-1, operated from 1948 and fuelled the first nuclear test RDS-1 in 1949. During the Cold War, 10 nuclear reactors were constructed, with a combined power of 7,333 MWth. Of these, four were used for plutonium production, yielding 31 tons of weapons-grade plutonium, out of the Soviet Union's all-time production of 145 tons. The other six reactors primarily produced tritium for thermonuclear weapons. In 1990, weapons-grade plutonium production was ceased.