Nuclear arms are the most powerful explosives created to date, with the ability to completely destroy a large city. A nuclear explosion is created by either splitting atoms (Fission), or merging tiny atom particles together (Fusion). The most commonly used isotope to create nuclear weapons is uranium-235 and plutonium-239.  

Within a second of detonation, a nuclear bomb creates a deadly fireball that instantly kills anyone within its radius. This is accompanied by the release of thermal energy, in the form of a blinding white light that can cause skin burns and eye damage. Further, radiation is produced that can cause damage to human cells, resulting in death or long-term implications such as cancer.  

The first nuclear bomb was developed at the end of the Second World War in 1945 by the United States, and subsequently two bombs were dropped on Japan that killed over 150,000 people combined. In response, the Soviet Union quickly developed its own nuclear bomb and an Arms Race started. The number of nuclear warheads peaked in 1986 with an estimated 64,000 spread across the world, which had the ability to completely destroy the world’s surface 3 times over.  

It is arguably this Mutually Assured Destruction (MAD), that prevented either the US or Soviet Union from ever actually using nuclear weapons during the Cold War, and consequently created global stability and peace to some extent. Although there were some close occasions such as the Cuban missile crisis (1961), and the NATO War Game codenamed operation Able Archer 83 (1983).  

Fast forward to today, eight countries (US, UK, Russia, France, China, India, Pakistan, North Korea) have nuclear weapons. Plus, Israel who is suspected of possessing nuclear arms, but has neither officially confirmed nor denied having them. Estimates put the number of active warheads today at roughly 10,000, with the US and Russia each having over 4,000, while the other individual countries have between 100-300.  

The main reason so few countries have developed nuclear capabilities is due to the Non-Proliferation Treaty that was signed in 1968 and stated that non-nuclear weapon countries would not ‘receive, manufacture, or acquire nuclear weapons’ in return for peaceful nuclear power information. Only North Korea has withdrawn from the treaty (2003), while India, Israel, Pakistan and South Sudan never signed it.  

Iran signed the treaty in both 1968 and 1995 when the treaty was extended indefinitely. However, the International Atomic Energy Agency reported in November 2003 that Iran had breached the terms of the treaty, by failing to follow its safeguards and not declaring its uranium enrichment program. Since then there have been high tensions between Iran and other nuclear countries. The Iran Nuclear deal in 2015 had partly de-escalated the tension, but President Trump criticised the deal, and subsequently withdrew from the agreement in 2018.  
In 2018, the US also withdrew from the Intermediate-Range Nuclear Forces Treaty that banned missiles with a range of 500-5500km. The Treaty had been an important agreement in ending the Cold War between the US and the Soviet Union, which was still in effect after Russia inherited it. The end of the Treaty has caused speculation of another Arms Race, with countries continuing to invest billions researching and developing nuclear weapons. This suggests that Nuclear arms will most likely continue to be a debated issue for the foreseeable future.