On 22 January 2021, the UN Treaty on the Prohibition of Nuclear Weapons entered into force, making nuclear weapons illegal under international law. With its entry into force we can finally call nuclear weapons what they are: prohibited weapons of mass destruction, just like chemical weapons and biological weapons.

Why this changes everything

Always immoral, now illegal

More than 75 years after the atomic bombings of Hiroshima and Nagasaki, the treaty banning these weapons of mass destruction under international law has finally entered into force.


The TPNW is the first globally applicable treaty that categorically prohibits these weapons and puts in place a framework for verifiably and irreversibly eliminating nuclear weapons, and for assisting the victims of their use and testing.

Building a new norm

The TPNW's entry into force strengthens the global taboo against the use and possession of nuclear weapons, rejecting the notion that these weapons are acceptable for some.


Even countries that were initially reluctant to come on board will feel the pressure from peers, parliamentarians and citizens alike to join the treaty and get on the right side of history. Find out how your country is doing


Cutting off their resources

Weapons that are banned by treaties quickly lose their legitimacy and get cut off from the resources for their production. For arms companies it's more difficult to acquire funds for work on illegal weapons, and such work carries a considerable reputational risk to investors like banks, insurers and pension funds. 


It's also becomes more controversial for the universities, scientists and companies providing the knowledge to aid the production, modernisation and deployment of nuclear weapons.  

Six things you can do to support the Treaty

Whether your country has already joined the treaty or not, we need your help to amplify the treaty and make sure that its impact is felt around the world.

Write a letter to the editor

Reach out to your newspaper about the importance of the TPNW. Speak from the heart, but also feel free to get some relevant background information:

Check out our booklet on the treaty’s entry into force.

Listen to the stories of the survivors of nuclear weapons use and testing

Start with the incredible journey of the hibakusha, from survivors of the bombings of Hiroshima and Nagasaki to banning the bomb. When you're done, share it far and wide.  

Pressure your elected officials

Your representatives at the local or national level are in the ideal position to speak out in support of the TPNW and call on your government to join the Treaty. 

ICAN Cities Appeal 
ICAN Parliamentary Pledge.  

Stop investments in nuclear weapons

Under the Nuclear Ban Treaty it will not only be illegal to produce nuclear weapons, it will also be illegal to bankroll them. Many banks are already getting ahead of the curve by pulling out of investing in companies that engage in nuclear weapons activities. Tell your bank:

Organise an event to mark Entry into Force Day.

All over the world, ICAN campaigners are getting ready to mark the day with stunts, gatherings, online events and more. If you are planning an event, make sure to add it to our global day of action map!

Add your event ›

Raise your voice on your social networks.

Spread the message with your friends. Choose a post we prepare for you, customise the message, and share it!

This is how we celebrated

The TPNW’s entry into force on 22 January 2021 was a victory for all people, made possible by decades of campaigning by civil society and the international community. So it’s no surprise that ICAN campaigners round the world, marked this  historic day with a wide range of activities, from commemorations to protests to educational events. All brought together in a fully-packed live streamed celebration from Geneva, Switzerland.






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Sydney - Jock and banners - credit Michelle Haywood