Nuclear Weapons

Nuclear weapons technology was developed during the 1930s and 1940s. The first nuclear weapons were detonated over Hiroshima and Nagasaki in August 1945. The devastating power of the bombs dropped on Japan forced the surrender of the Japanese. Since then, controlling the proliferation of nuclear weapons has been an important issue in international relations and the two detonations in Japan remained the only ever usage in warfare.

This entries details the development of nuclear technology, the number of warheads and the number of countries with nuclear capabilities.

Empirical View

There are two common ways of understanding the development of nuclear weapons and the arms race that took place between the US and the Soviet Union during the Cold War.

Nuclear weapons over time

The first is to look at the stockpiles of nuclear weapons each superpower built up. The total number of nuclear weapons in the world peaked in 1986. It is also worth remembering that the destructive power of each nuclear warhead has increased significantly since the first atomic weapons used in the Second World War. What is more, the number of states with confirmed nuclear capabilities now includes the US, Russia, UK, France, China, India, Pakistan, Israel and North Korea.1

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Nuclear weapons test

If we consider the number of nuclear weapons tests, we can see that the Cold War was a very active period of nuclear weapons development. Although nuclear weapons were only ever used in warfare during the Second World War, there have been over 2000 nuclear weapons tests since then. Most recently North Korea conducted nuclear weapons tests in 2006, 2009 and 2013.

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World map of nuclear weapons test

The location of these nuclear weapons tests is shown on this world map by cartographer Bill Rankin.

World map of nuclear explosions, 1945-2007 – Bill Rankin (2007)2

Nuclear explosions around the world since 1945

Japanese artist Isao Hashimoto has created a time lapse map that shows every nuclear explosion between 1945 and 1998. You can watch the video below.

Nuclear Powers

It is a common misconception that more and more nations are exploring and developing nuclear weapons since the Second World War. As the following graph demonstrates, there have been peaks in nuclear weapon development in the past few decades. By the late 1980s, the number of nations developing nuclear weapons started falling and has remained steady since the mid-1990s.

The names in the graph below represent nations developing weapons, and countries marked with “-” represent the year in which development in that country ceased.

Non-nuclear states that started and stopped exploring nuclear weapons, 1945-2010 – Pinker3

Nonnuclear States that Started and Stopped Exploring Nuclear Weapons, 1945–2010 - Pinker0

Data Quality & Definitions

Obtaining an accurate count of the nuclear warheads possessed by each country today is difficult, since each country controls the publicly available information relating to its nuclear capabilities for security reasons. The data presented here is taken from the Federation of American Scientists Nuclear Notebook and should be taken as a best-estimate of the capabilities of each country. In addition to this, Israel maintains a policy of nuclear ambiguity and refuses to confirm or deny its nuclear capabilities.

The data on nuclear weapons tests come from the Oklohoma Geological Survey and can be considered an accurate count of nuclear weapons tests.

Data Sources

Federation of American Scientists: Nuclear Notebook
  • Data: Estimate of the nuclear warhead inventory and capability of each nuclear power
  • Geographical coverage: Confirmed and suspected nuclear powers
  • Time span: 1945-2014
  • Available at: Online here

Johnston’s Archive of Nuclear Tests
  • Data: Nuclear tests, above ground nuclear detonations, high-altitude nuclear explosions and fatalities
  • Geographical coverage: Global
  • Time span: Since 1945
  • Available at: Online here

Oklahoma Geological Survey Nuclear Explosion Catalog
  • Data: Depth, magnitude, latitude and longitude of nuclear explosions
  • Geographical coverage: Global
  • Time span: 1945-1998
  • Available at: Online here