Category: International Campaign to Abolish Nuclear Weapons (ICAN)

The U.N. Treaty on the Prohibition of Nuclear Weapons

The U.N. Treaty on the Prohibition of Nuclear Weapons

On 7 July 2017 – following a decade of advocacy by ICAN and its partners – an overwhelming majority of the world’s nations adopted a landmark global agreement to ban nuclear weapons, known officially as the Treaty on the Prohibition of Nuclear Weapons. On 22 January 2021, the treaty will enter into force.

Prior to the treaty’s adoption, nuclear weapons were the only weapons of mass destruction not subject to a comprehensive ban, despite their catastrophic, widespread and persistent humanitarian and environmental consequences. The new agreement fills a significant gap in international law.


It prohibits nations from developing, testing, producing, manufacturing, transferring, possessing, stockpiling, using or threatening to use nuclear weapons, or allowing nuclear weapons to be stationed on their territory. It also prohibits them from assisting, encouraging or inducing anyone to engage in any of these activities.


A nation that possesses nuclear weapons may join the treaty, so long as it agrees to destroy them in accordance with a legally binding, time-bound plan. Similarly, a nation that hosts another nation’s nuclear weapons on its territory may join, so long as it agrees to remove them by a specified deadline.


Nations are obliged to provide assistance to all victims of the use and testing of nuclear weapons and to take measures for the remediation of contaminated environments. The preamble acknowledges the harm suffered as a result of nuclear weapons, including the disproportionate impact on women and girls, and on indigenous peoples around the world.


The treaty was negotiated at the United Nations headquarters in New York in March, June and July 2017, with the participation of more than 135 nations, as well as members of civil society. It opened for signature on 20 September 2017. It is permanent in nature and will be legally binding on those nations that join it.

The World’s Nuclear Weapons

The World’s Nuclear Weapons

A single nuclear warhead could kill hundreds of thousands of people, with lasting and devastating humanitarian and environmental consequences. Russia, the United States, the United Kingdom, France, China, India, Pakistan, Israel and North Korea possess an estimated total of nearly 14,000 nuclear weapons, most of which are many times more powerful than the nuclear weapon dropped on Hiroshima. Thirty-one other states are also part of the problem. 

Learn more about all of the countries that support nuclear weapons.

Nuclear Weapons History

Nuclear Weapons History

Nuclear Weapons History

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Why a Ban?

Why a Ban?

Nuclear weapons are the most inhumane and indiscriminate weapons ever created. That is why it is time to end them, before they end us.

Nuclear weapons are the most inhumane and indiscriminate weapons ever created. They have catastrophic humanitarian and environmental consequences that span decades and cross generations; they breed fear and mistrust among nations, as some governments can threaten to wipe out entire cities in a heartbeat; the high cost of their production, maintenance and modernisation diverts public funds from health care, education, disaster relief and other vital services. Banning these immoral, inhumane weapons under international law was a critical step along the path to ending them. 

With the adoption of the UN Treaty on the Prohibition of Nuclear Weapons (TPNW) on July 7th, 2017, the world’s majority took a critical step towards making that nuclear-weapon-free future a reality. 

Read more about how the TPNW works >

The Catastrophic Harm of Nuclear Weapons

The Catastrophic Harm of Nuclear Weapons

Nuclear weapons are the most destructive, inhumane and indiscriminate weapons ever created. Both in the scale of the devastation they cause, and in their uniquely persistent, spreading, genetically damaging radioactive fallout, they are unlike any other weapons. A single nuclear bomb detonated over a large city could kill millions of people. The use of tens or hundreds of nuclear bombs would disrupt the global climate, causing widespread famine.

What makes nuclear weapons the worst

1 A single nuclear weapon can destroy a city and kill most of its people. Several nuclear explosions over modern cities would kill tens of millions of people. Casualties from a major nuclear war between the US and Russia would reach hundreds of millions.

Modeling the effects on cities →
Hiroshima and Nagasaki bombings →

2 The extreme destruction caused by nuclear weapons cannot be limited to military targets or to combatants.

Blast, heat and radiation →
Outlawing inhumane weapons →

3 Nuclear weapons produce ionizing radiation, which kills or sickens those exposed, contaminates the environment, and has long-term health consequences, including cancer and genetic damage.

The legacy of nuclear testing →
Nuclear weapons production →

4 Less than one percent of the nuclear weapons in the world could disrupt the global climate and threaten as many as two billion people with starvation in a nuclear famine. The thousands of nuclear weapons possessed by the US and Russia could bring about a nuclear winter, destroying the essential ecosystems on which all life depends.

Climate disruption and famine →

5 Physicians and first responders would be unable to work in devastated, radioactively contaminated areas. Even a single nuclear detonation in a modern city would strain existing disaster relief resources to the breaking point; a nuclear war would overwhelm any relief system we could build in advance. Displaced populations from a nuclear war will produce a refugee crisis that is orders of magnitude larger than any we have ever experienced.

No humanitarian response →

6 Whether or not they are detonated, nuclear weapons cause widespread harm to health and to the environment.

7 Spending on nuclear weapons detracts limited resources away from vital social services. 

Diversion of public resources→

Learn more about these issues and join ICAN’s effort.

The TPNW: How is your country doing?

The TPNW: How is your country doing?

Find out if your country has joined the Treaty on the Prohibition of Nuclear Weapons – and which cities, parliamentarians, and local organisations are supporting it.

How is your country doing?

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ICAN Tools for Activists and Campaigners

ICAN Tools for Activists and Campaigners

ICAN Tools for Activists and Campaigners

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