Nuclear weapons are explosive devices that derive from nuclear reactions. These reactions release energy from small amounts of matter. Even a small nuclear device can devastate an entire city. The impact of a nuclear bomb can be felt for years after it explodes, as the radiation and gases from the bomb continue to make people sick.
- There are 16,400 nuclear weapons on Earth today, more than 20 years after the Cold War ended.
- Five states are declared as nuclear weapon zones under the Non-Proliferation Treaty: US, UK, France, Russia and China. These countries are committed to disarmament under international law. It is illegal for any other country that has signed the NPT to develop these weapons.
- Many other countries have been suspected of developing nuclear weapons including India, Pakistan, Israel, Iraq, Iran, Libya, Syria and Korea.
- The US has nuclear weapons deployed across Europe for use by all NATO allies, including the UK.
- Britain has one nuclear weapon system, Trident. Trident replaced Polaris in the 1980s and consists of four submarines, each one capable of carrying 16 missiles. Each warhead on the missiles can be guided to a separate target.
- The only nuclear bombs ever to be used were by the US against Japan. In 1945 nuclear bombs were dropped on the Japanese cities of Hiroshima and Nagasaki, killing and injuring hundreds of thousands of people. Today Hiroshima’s peace park attracts visitors from across the world.
- Trident is more than 1,000 times powerful than the bomb that hit Hiroshima. Each warhead’s destructive power is measured in kilotons (kts). A kiloton is equal to 1,000 tons of TNT. The Hiroshima bomb was 16kts. Trident is far more deadly – each warhead is up to 100kts and there are 160 of them. That’s 16,000kts.
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1942: The US, afraid that Hitler is developing nuclear weapons in Germany, begins the Manhattan Project to build their own nuclear bomb. Physicist Joseph Rotblat resigns from the project in 1944, when he discovers Germany will not develop nuclear weapons. He is banned from the US for 20 years.
16 July 1945: The world’s first nuclear test is conducted by the US. Three weeks later they use a nuclear bomb against an enemy for the first time, exploding ‘Little Boy’ above the Japanese city of Hiroshima killing 140,000 people. On 9 August 1945, a second nuclear bomb is exploded above Nagasaki causing 74,000 deaths.
January 1946: The United Nations passes its first resolution calling for the elimination of all weapons of mass destruction (WMD). Yet many countries still begin research and nuclear tests.
1950s: The number of warheads on the planet reaches 5,015 with the majority owned by the US (4,600) and the Soviet Union (400). Tensions rise between these two world ‘superpowers’ and the Cold War begins. For the next 40 years both sides argue that the threat of retaliation is enough to ensure their nuclear weapons will never be used. The situation becomes known as ‘mutually assured destruction’ (MAD), yet both sides remain on constant alert.
1953: The four-minute warning is introduced by the British Government to ensure that in the event of a nuclear war a siren will sound indicating the human race has four minutes left to live.
1958: Both superpowers agree to stop nuclear testing, but both begin testing again in 1961 despite signing a joint agreement for general and complete disarmament.
16–29 October 1962: The Cuban Missile Crisis nearly provokes a nuclear war as the US begins a 13-day confrontation with the USSR when it discovers their missiles in Cuba, just 90 miles from the US coast. The Soviets step back at the last moment.
1 July 1968: The Non-Proliferation Treaty (NPT) is signed. The Treaty is the first in which non-nuclear-weapon states agree never to acquire nuclear weapons, and the nuclear-weapon states make a legal undertaking to disarm.
1969: The US and the USSR begin talks on armament control known as Strategic Arms Limitation Talks (SALT), leading to the first Anti-Ballistic Missile Treaty (a ballistic missile can deliver one or more warheads to a predetermined target). A few months later, the US deploys its first missile with independently targeted warheads, meaning that each nuclear warhead can be fired at a different target.
1980: The number of warheads on the planet reaches more than 65,000, with all but a thousand held by the US and USSR.
1985: Mikhail Gorbachev becomes the Soviet leader and revives negotiations to get rid of nuclear weapons. Over the next few years Gorbachev’s reforms lead to the end of the Cold War, the reunification of Germany, the withdrawal of Soviet troops from Eastern Europe and the collapse of the Soviet Union.
1987: The Intermediate-Range Nuclear Forces Treaty (INF) is introduced, the first treaty to get rid of existing WMD.
1991: The Gulf War leads to fears that Iraq could use chemical or biological weapons on Israel, which might retaliate with nuclear weapons. Iraq fires Scud missiles into Israel but they have conventional warheads (not nuclear, chemical or biological materials).
1995: Joseph Rotblat, the physicist banned from the US after quitting the Manhattan Project, is awarded the Nobel Peace Prize for his work towards nuclear disarmament.
July 1996: The World Court states it is illegal for a country to use nuclear weapons unless the very existence of that country is at stake. Nuclear weapon states do nothing to show they accept or acknowledge the opinion.
1998: India begins a series of nuclear tests. Pakistan responds with tests of its own. Neither country has signed the NPT or the Comprehensive Test Ban Treaty (CTBT) .
2000: Nuclear weapon states sign a document outlining 13 steps towards nuclear disarmament and the world’s media announce we are going to see the end of nuclear weapons.
2002: The US government publishes details of when they will use nuclear weapons against non-nuclear weapon states. In the build up to the war on Iraq, Britain comments on using nuclear weapons in response to a chemical or biological attack on British troops.
20 March 2003: The US leads the invasion of Iraq amid claims Iraq’s WMD pose a threat to their security, despite the UN finding no evidence of WMD in Iraq. A subsequent investigation finds Iraq ended its WMD programmes in 1991 but intended to resume production if their sanctions were lifted.
2004: Joseph Rotblat launches WMD Awareness in response to changes to nuclear policy in the run-up to the Iraq war.
2009: North Korea announces it has conducted an underground nuclear test.
2013: North Korea threatens to use its nuclear arsenal in combat against South Korea and the US.
2016: The UK government will decide whether to renew its nuclear weapons system, Trident.
- China: 240 warheads
- France: 300 warheads
- Russia: 10,000-12,600 warheads
- United Kingdom: 180 warheads
- United States: 9,613 warheads
- India: 100 nuclear warheads
- Israel: 75-200 nuclear warheads
- Pakistan: 70-90 nuclear warheads
- Korea: Unknown
Source: Arms Control Association
Most of what is known about the effects of nuclear weapons comes from the bombs dropped on the Japanese cities of Hiroshima and Nagasaki in 1945, atmospheric nuclear testing and nuclear accidents which continue to effect people to this day. Although there are different types of nuclear weapons with varying amounts of explosive power, their effects are the same. So what happens when a nuclear weapon explodes?
- The temperature of a nuclear explosion is several million degrees centigrade. The explosion creates a fireball of white heat.
- The mushroom cloud effect is produced by the powerful updrafts lifting debris from the ground up into the air. The top of the cloud can be several kilometres wide.
- Intense heat and radiation is released, travels in winds of around 1,000mph, and falls from the sky. This is known as nuclear fallout. The amount depends on what sort of nuclear explosion occurs. The Hiroshima bomb was an ‘air-burst’, increasing the effects from the heat and blast. Meanwhile a ‘ground-burst’ causes larger quantities of radioactive debris: in the aftermath of the explosion at the nuclear power plant at Chernobyl, Ukraine, in 1986 radioactive rain fell across northern Europe reaching as far as north Wales and Scotland.
The effect this has on the human body is horrific. At Hiroshima the only remains of people caught outdoors within a half-mile radius of the bomb were their shadows burnt into stone. Under these extreme conditions the human body melts both internally and externally.
Those in buildings or otherwise shielded were indirectly killed by the blast and heat effects as buildings collapsed and all inflammable materials burst into flames. Thousands more suffered from extreme injuries including non-survivable burns, blindness, bleeding from glass splinters and internal injuries. Many of those with survivable injuries did not survive because all rescue and medical services were destroyed.
People who were further away were affected by radioactive fallout. Exposure to high levels of radiation can cause bleeding from the mouth, gangrenous ulcers, hair loss, internal bleeding, vomiting, fever, delirium and terminal coma. There is no effective treatment. The longer-term effects include foetuses being born with deformities and disabilities, damage to the immune system and major scars.
For survivors there is a serious risk of developing cancer and that their children will have birth defects or leukaemia and other cancers. However this has not been reported in the children of Hiroshima and Nagasaki survivors.
Since the 1960s a number of treaties have been created to control the world’s use of nuclear weapons through international law. Early treaties included the Outer Space Treaty, banning the use of nuclear weapons in space, and Latin America becoming a nuclear weapon-free zone, both signed in 1967. Since then important treaties have included:
1968 – Nuclear Non-Proliferation Treaty (NPT)
This aimed to stop the spread or proliferation of nuclear weapons. Countries that had tested nuclear weapons at the time had to sign as a Nuclear Weapon State (NWS) and agree not to pass nuclear weapons technology on to Non-Nuclear Weapon States (NNWS), and to disarm. The NNWS had to promise not to make any attempt to produce nuclear weapons. If they stuck to this they could get help with the development of a nuclear power programme. The treaty is now reviewed every five years.
- Entered into force: 1970
- Number of countries signed: 188
- Not signed: India, Pakistan, Israel, Cook Islands, Niue. North Korea (DPRK) announced in January 2003 that it was withdrawing from the NPT. It later suspended that withdrawal. It is now believed to be developing nuclear weapons.
2000: The NWS agree a 13 step plan towards nuclear disarmament: “An unequivocal undertaking by the nuclear-weapon States to accomplish the total elimination of their nuclear arsenals leading to nuclear disarmament to which all States parties are committed.”
2005: The conference is deemed a failure as no agreements can be reached and great hopes are placed on the 2010 Conference.
2010: It is felt that, with US President Obama and Russian President Dmitry Medvedev committed to nuclear abolition, circumstances are right for a better outcome on all aspects of the treaty including: nuclear disarmament; non-proliferation of nuclear weapons; peaceful use of nuclear energy; and creating a zone free of nuclear and other WMD in the Middle East. An Outcome Document is produced with 64 action points agreed by all states present. The Conference reaffirms the validity of the 13 Practical Steps agreed in 2000.
2015: The next conference is due to take place a year ahead of the UK Government’s vote on renewing Trident.
1996 – Comprehensive Test Ban Treaty (CTBT)
This treaty outlaws nuclear testing of any kind. It has taken years of negotiation because it needs to be signed and ratified by all 44 countries identified as having nuclear power plants or research reactors. Countries that possess nuclear weapons who have not yet ratified the treaty are China, India, Israel, Pakistan, North Korea and the US. Those who have signed include France, one of the five NWS.
- Opened for signature: 1996
- Entered into force: Pending
- Number of countries signed: 182
- Number of countries ratified: 153
- Number of countries not signed: 13
1992: The US, Russia and France agree a temporary halt on nuclear testing. Britain has no choice but to join in as it is using Nevada as a test site.
1994: Negotiations for a CTBT begin but China is already conducting a series of tests and France is about to begin a series of tests. Britain supports the French. The US and Russia take the lead despite opposition among scientists and the military.
1996: CTBT opens for signing. Ways of verifying that the treaty is being followed include monitoring stations to spot large underground explosions, tracking of gases escaping into the atmosphere, and satellites to track vehicle movements. There will not be worldwide coverage until the CTBT is fully signed and enters into force. The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is set up in Vienna, Austria, to build up the verification regime of the CTBT in preparation for the Treaty’s entry into force.
2013: The US has the technology to carry out simulated tests on computers, and it does so regularly to develop new nuclear warheads. It also carries out ‘sub-critical’ tests, sometimes jointly with the UK. These tests use chemical explosives and less than a kilo of plutonium but do not produce a nuclear explosion. Although this does not break the terms of the CTBT it damages the chances of other countries signing up to the treaty.
2003 – Strategic Offensive Reduction Talks (SORT)
Agreed and signed by the US and Russia to ensure each side reduced their nuclear weapons to between 1,700 and 2,200 ‘operationally deployed’ warheads by the end of 2012. The treaty was due to expire but was replaced with the new START treaty in 2011. If it had not been replaced, either side could have given three months notice of withdrawal without having done anything at all to reduce the number of weapons.
2011 – New Strategic Arms Reduction Treaty (New START)
US President Barack Obama signed ratification documents for this arms treaty with Russia that reduces both nations’ nuclear arsenals and bolster verification mechanisms. The treaty brings down the numbers of strategic nuclear weapons in both countries to 1,550 warheads and 700 launchers. It also allows for a resumption of inspections of each country’s nuclear arsenal.
Fissile Material Cut-off Treaty
Many countries have been calling for a ban on the continued production of fissile materials – the key ingredient for producing nuclear weapons. The issue has been on the UN’s agenda since 1957. A major obstacle to negotiations has been the issue of existing stocks. While some states – including the US, UK and Japan – favour a treaty that limits future production of fissile materials, other states, such as those belonging to the NNWS, believe the treaty should address fissile materials already produced and stockpiled. This would require the NWS, including the UK, to ensure existing stocks of fissile materials can never be used as weapons again.