On Friday 23rd October, at the UN and in an online event organised by the Permanent Missions of Austria, Brazil, Costa Rica, Indonesia, Ireland, Mexico, New Zealand, Nigeria, South Africa and Thailand, in collaboration with ICAN, the International Campaign to Abolish Nuclear Weapons, it was announced that Jamaica and Nauru had ratified the Treaty on the Prohibition of Nuclear Weapons (TPNW) bringing the total to 49. On Saturday afternoon, Honduras also deposited its instrument of ratification bringing the total to 50 thus triggering the treaty’s entry into force in 90 days’ time on the 22nd of January 2021.

The implications of this treaty are enormous as it brings into international law a prohibition on the most destructive of all weapons ever invented. Under the terms of the treaty it will be illegal for States parties to “develop, test, produce, acquire, possess, stockpile, use or threaten to use nuclear weapons”. Furthermore the Treaty also obliges States parties to provide adequate assistance to individuals affected by the use or testing of nuclear weapons, as well as to take necessary and appropriate measures for environmental remediation as a result of activities related to the testing or use of nuclear weapons.

This new piece of international law effectively fills a legal gap that has remained in place since the 1970 Nuclear Non-Proliferation Treaty (NPT). Under the terms of that treaty, five states—the USA, the Russian Federation, China, France and the United Kingdom—were recognised as nuclear powers and all other countries were pressured into renouncing nuclear weapon programmes in return for the promise of “peaceful uses of nuclear technology”. However article VI of that treaty says:

“Each of the Parties to the Treaty undertakes to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control.”

And, campaigners around the world have been pushing for the nuclear powers to make good on their promise ever since.

In the meantime, four other nations who either never signed the NPT (India, Pakistan, Israel) or withdrew from it (North Korea) went on to develop their own nuclear weapons, leaving the NPT in a kind of perpetual limbo in which the original five nuclear armed states refuse to even talk about disarmament until the other four join the NPT after having given up their weapons. This is something that will clearly never happen considering the current state of global geopolitics with constant tension between India and Pakistan over the state of Kashmir, between India and China over their border dispute, between North Korea and the United States in a conflict dating back to the 1950s, and last, but by no means least, between Israel and many countries of the Arab world.

Despite the fact that every five years, States parties to the NPT meet to assess progress and to plan further advances, the process has been completely paralysed as a result of the treaty never gaining the universal adherence that it required.

The only time the legality of nuclear weapons was challenged dates back to 1996 when a group of campaigners took a case to the International Court of Justice in The Hague. The judges in that case established that nuclear weapons were illegal unless the very existence of a State were under threat. This loophole the size of a truck enabled the nuclear armed states to cling onto their weapons.

Now, the TPNW changes the legal landscape for ever and is a radical evolution of existing international law because it closes that loophole. It prohibits the use of nuclear weapons under any circumstances.

Such is the fear that this new treaty has generated that in the days before the 50th ratification being received the United States took the unprecedented step of writing to all TPNW States parties and asked them to withdraw their instruments of ratification. Maybe these are the last death throes of the Trump administration, but Trump didn’t invent the United States’ reliance on nuclear weapons, he’s just following the same line that has been taken by every US administration since Harry Truman was president.

It is easy to foresee that, as more and more nations get frustrated at the intransigence of the nuclear powers, one-by-one they may choose to abandon the NPT and instead put their faith in the TPNW that treats all States parties equally and provides a pathway for a nuclear armed state to ratify the TPNW and subsequently undertake a process of disarmament.

The new legal landscape will undoubtedly have an impact in other fields, and in fact such effects have already been seen. Several financial institutions, sensitive to the opinions of their customers, have already divested from corporations that make profit from the production of nuclear weapons. The Don’t Bank on the Bomb campaign has reported a number of successful occasions on which pension funds and banks have turned their backs on profits from unethical sources. Furthermore, campaigns in nuclear weapon states and in states (such as non-nuclear NATO members) who pretend that they rely on nuclear weapons for their security will be enormously boosted as the stigmatization of nuclear weapons gains ground as a result of their illegality, putting pressure on parliamentarians to change national defence policies.

This may not be the best treaty in the world. As more and more nations join there may be a need to enhance it or even replace it. Certainly the fact that the preamble enshrines the right to exploit nuclear energy despite the fact that it is toxic, that it can escape human control with unfathomable consequences for the planet—as we’ve seen previously in Chernobyl and Fukushima—and that it is the requisite precursor for extracting the plutonium needed for nuclear bombs, remains problematic.

But today is a day for rejoicing and celebration as the world takes one more collective step towards a world free of nuclear weapons. As Setsuko Thurlow, the Hiroshima survivor and tireless campaigner said in her speech at the Nobel Peace Prize ceremony in 2017, “Let this be the beginning of the end of nuclear weapons.”