This timeline of nuclear weapons development is a chronological catalog of the evolution of nuclear weapons rooting from the development of the science surrounding nuclear fission and nuclear fusion. In addition to the scientific advancements, this timeline also includes several political events relating to the development of nuclear weapons. The availability of intelligence on recent advancements in nuclear weapons of several major countries (such as United States and the Soviet Union) is limited because of the classification of technical knowledge of nuclear weapons development.
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion reactions, producing a nuclear explosion. Both bomb types release large quantities of energy from relatively small amounts of matter.
The Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT, is an international treaty whose objective 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.
Nuclear proliferation is the spread of nuclear weapons, fissionable material, and weapons-applicable nuclear technology and information to nations 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. 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, de-stabilize international or regional relations, or infringe upon the national sovereignty of nation states.
Nuclear disarmament is the act of reducing or eliminating nuclear weapons. Its end state can also be a nuclear-weapons-free world, in which nuclear weapons are completely eliminated. The term denuclearization is also used to describe the process leading to complete nuclear disarmament.
North Korea has a military nuclear weapons program and, as of early 2020, is estimated to have an arsenal of approximately 30 to 40 nuclear weapons and sufficient production of fissile material for six to seven nuclear weapons per year. North Korea has also stockpiled a significant quantity of chemical and biological weapons. In 2003, North Korea withdrew from the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). Since 2006, the country has been conducting a series of six nuclear tests at increasing levels of expertise, prompting the imposition of sanctions.
Nuclear weapons possess enormous destructive power from nuclear fission, or a combination of fission and fusion reactions. Building on major scientific breakthroughs made during the 1930s, the United States, the United Kingdom, Canada, and France collaborated during World War II, in what was called the Manhattan Project, to build a weapon using nuclear fission, also known as an atomic bomb. In August 1945, the atomic bombings of Hiroshima and Nagasaki were conducted by the United States against Japan at the close of that war, standing to date as the only use of nuclear weapons in hostilities.
Nuclear weapons tests are experiments carried out to determine the performance, yield, and effects of nuclear weapons. Testing nuclear weapons offers practical information about how the weapons function, how detonations are affected by different conditions, and how personnel, structures, and equipment are affected when subjected to nuclear explosions. However, nuclear testing has often been used as an indicator of scientific and military strength. Many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status through a nuclear test.
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 none engaged in warhead production on nearly the same scale as the two superpowers.
The Russian Federation is known to possess or have possessed three types of weapons of mass destruction: nuclear weapons, biological weapons, and chemical weapons. It is one of the five nuclear-weapon states recognized under the Treaty on the Non-Proliferation of Nuclear Weapons.
The People's Republic of China has developed and possesses weapons of mass destruction, including chemical and nuclear weapons. The first of China's nuclear weapons tests took place in 1964, and its first hydrogen bomb test occurred in 1967 at Lop Nur. Tests continued until 1996, when China signed the Comprehensive Nuclear-Test-Ban Treaty (CTBT), but did not ratify it. China acceded to the Biological Weapons Convention (BWC) in 1984 and ratified the Chemical Weapons Convention (CWC) in 1997.
Pakistan is one of nine states that possess nuclear weapons. Pakistan began developing nuclear weapons in January 1972 under Prime Minister Zulfikar Ali Bhutto, who delegated the program to the Chairman of the Pakistan Atomic Energy Commission (PAEC) Munir Ahmad Khan with a commitment to having the device ready by the end of 1976. Since PAEC, which consisted of over twenty laboratories and projects under reactor physicist Munir Ahmad Khan, was falling behind schedule and having considerable difficulty producing fissile material, Abdul Qadeer Khan, a metallurgist working on centrifuge enrichment for Urenco, joined the program at the behest of the Bhutto administration by the end of 1974. As pointed out by Houston Wood, "The most difficult step in building a nuclear weapon is the production of fissile material"; as such, this work in producing fissile material as head of the Kahuta Project was pivotal to Pakistan developing the capability to detonate a nuclear weapon by the end of 1984.
The Soviet atomic bomb project was the classified research and development program that was authorized by Joseph Stalin in the Soviet Union to develop nuclear weapons during and after World War II.
The United States was the first country to manufacture nuclear weapons and is the only country to have used them in combat, with the bombings of Hiroshima and Nagasaki in World War II. Before and during the Cold War, it conducted 1,054 nuclear tests, and tested many long-range nuclear weapons delivery systems.
A thermonuclear weapon, fusion weapon or hydrogen bomb is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lower mass, or a combination of these benefits. Characteristics of nuclear fusion reactions make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as uranium-235 or plutonium-239. The first full-scale thermonuclear test was carried out by the United States in 1952; the concept has since been employed by most of the world's nuclear powers in the design of their weapons.
Project 596, was the first nuclear weapons test conducted by the People's Republic of China, detonated on 16 October 1964, at the Lop Nur test site. It was a uranium-235 implosion fission device made from weapons-grade uranium (U-235) enriched in a gaseous diffusion plant in Lanzhou.
Saudi Arabia is not known to have a nuclear weapons program. From an official and public standpoint, Saudi Arabia has been an opponent of nuclear weapons in the Middle East, having signed the Treaty on the Non-Proliferation of Nuclear Weapons, and is a member of the coalition of countries demanding a Nuclear-weapon-free zone in the Middle East. Studies of nuclear proliferation have not identified Saudi Arabia as a country of concern. Nuclear technology company IP3 International was formed in June 2016 to transfer nuclear technology from the United States to Saudi Arabia.
The State of Israel is widely believed to possess nuclear weapons. Estimates of Israel's stockpile range between 80 and 400 nuclear warheads, and the country is believed to possess the ability to deliver them in several methods, including by aircraft, as submarine-launched cruise missiles, and via the Jericho series of intermediate to intercontinental range ballistic missiles. Its first deliverable nuclear weapon is thought to have been completed in late 1966 or early 1967; which would make it the sixth country in the world to have developed them.
Saudi Arabia has not officially maintained and possessed weapons of mass destruction (WMD). In 1972 Saudi Arabia signed and approved the convention on the prohibition of the development, production and stockpiling of biological (bacteriological) and toxin weapons. Nevertheless, Saudi Arabia has made steps towards a nuclear program and according to some observations, they can be used to develop nuclear weapons. According to some reports, Riyadh has an alleged deal with Pakistan regarding nuclear weapons projects.