Today, the UN Treaty on the Prohibition of Nuclear Weapons (TPNW) enters into force, becoming international law. Nuclear weapons are, as of now, unlawful to possess, develop, deploy, test, use, or threaten to use. While the Treaty’s provisions are legally binding on its states parties, its normative force is growing every day, establishing customary international law that will over time impact the policies and practices of all governments.

“This achievement shows us what happens when those committed to multilateralism and transnational activism work together to change the world,” says WILPF’s disarmament director Ray Acheson. “The TPNW, the first feminist law on nuclear weapons, disrupts the politics and economics of nuclear weapons and challenges the core tenants of nuclearism. It is instrumental in our pursuit of nuclear abolition.”

For the last decade, the International Campaign to Abolish Nuclear Weapons (ICAN), of which WILPF is a steering group member, has been working with officials from non-nuclear countries to prohibit nuclear weapons. Despite incredible pressure from several of the nuclear-armed states, the UN General Assembly adopted the TPNW on 7 July 2017, and later that year ICAN went on to win the Nobel Peace Prize.

From the time the Treaty opened for signature in September 2017 to when it reached the fifty national ratifications necessary to secure its entry into force in October 2020, the Treaty has increased in its appeal to people around the world. While much work remains to achieve the elimination of nuclear weapons, their prohibition is a crucial step.

The TPNW stigmatises nuclear weapons, making it more difficult for nuclear-armed states to justify their possession and defend their “deterrence” doctrines. We have seen this work with other weapon bans, including on landmines and cluster munitions. We have likewise seen stigmatisation of destructive and unjust policies help to change behaviour and laws in relation to civil rights, women’s rights, and LGBTQ+ rights.

“As past social movements have taught us, change doesn’t happen in instant—it is iterative, contested, and must be constantly defended and built upon,” explains Acheson. “Over time, the Treaty will have a normative impact on the behaviour of other countries, regardless of whether they join, and on financial institutions and other national and local actors.”

Already, more than 1,600 elected officials in countries that have not yet joined the TPNW have pledged to work to get their government on board. Cities and towns around the world have adopted resolutions encouraging their governments to join the Treaty, including capitals in nuclear-armed states like Paris and Washington, DC. Financial institutions have started divesting from nuclear weapons producing companies, including within countries that have not yet joined the Treaty. Public support is also already behind the ban. Public opinion polls show that 79 percent of Australians, 79 percent of Swedes, 78 percent of
Norwegians, 75 percent of Japanese, 84 percent of Finns, 70 percent of Italians, 68 percent of Germans, 67 percent of French, and 65 percent of Americans support their government joining the TPNW.

The hope for nuclear abolition lies in the efforts of all activists for social justice. While we have a long path to achieve the elimination of nuclear weapons, Hiroshima survivor Setsuko Thurlow has said, “with the Treaty on the Prohibition of Nuclear Weapons, we can be certain that that beautiful day will dawn.”

WILPF has opposed nuclear weapons since the start of the nuclear age in 1945. Its members around the world have held actions to protest nuclear weapon testing and development, to demand disarmament and arms control, and to highlight the horrific humanitarian consequences of nuclear weapons. Today, as the TPNW enters into force, WILPF Sections and Groups are celebrating along with other ICAN partners. See icanw.org/events for details.