The Treaty on the Prohibition of Nuclear Weapons (TPNW) was inspired by the “humanitarian initiative”- an informal effort by a range of States to reframe the debate on nuclear weapons and place greater emphasis on the catastrophic and lasting consequences of their use on health, societies and the environment.
A key part of the initiative was a series of conferences on the humanitarian impacts of nuclear weapons, which were held in Oslo (2013), Nayarit (2014) and Vienna (2014). These conferences provided new information on the immediate and long-term effects of nuclear weapons and the dangers associated with their potential use and continued possession.
The observations and conclusions inspired several UN General Assembly (UNGA) resolutions focused on the humanitarian-related aspects of nuclear weapons. These included resolutions on the humanitarian consequences of nuclear weapons, the humanitarian pledge for the prohibition and elimination of nuclear weapons and the ethical imperatives for a nuclear-weapon-free world.
Ways to advance nuclear disarmament were also being considered. The UNGA authorized an Open-ended Working Group to look at various aspects of this issue, which met in 2013 and 2016. The final report of the 2016 Group included a recommendation for the UN General Assembly to convene a conference in 2017, open to all States, with the participation and contribution of international organizations and civil society, to negotiate a legally binding instrument to prohibit nuclear weapons, leading to their total elimination.
The UNGA subsequently authorized the convening of a UN conference in 2017 to negotiate such an instrument. The UN conference to negotiate a legally binding instrument to prohibit nuclear weapons met in March and June/July 2017. At the close of the negotiations 122 States voted to adopt the Treaty on the Prohibition of Nuclear Weapons, 1 State opposed and 1 abstained. The Treaty was opened for signature as of 20 September 2017.
On 24 October 2020, the conditions for the entry into force of the Treaty were met. Accordingly, the Treaty shall enter into force on 22 January 2021, in accordance with its article 15, paragraph 1, which reads as follows:
“This Treaty shall enter into force 90 days after the fiftieth instrument of ratification, acceptance, approval or accession has been deposited.”