An international treaty banning all nuclear weapons that has been signed by 51 countries and that campaigners hope will help raise the profile of global deterrence efforts comes into force on Friday. Although in some respects the step is largely symbolic because the world’s nuclear powers have not signed up, the treaty will be legally binding on the smaller nations that have endorsed it, and it is backed by the UN leadership. The treaty on the prohibition of nuclear weapons (TPNW) outlaws the creation, ownership and deployment of nuclear weapons by signatory states and places obligations on them to assist other victims of nuclear weapons use and testing. Britain’s Campaign for Nuclear Disarmament has released polling saying that 59% of the UK public support the country signing up to the TPNW and that 77% support a “total ban on all nuclear weapons globally”. Kate Hudson, CND’s general secretary, called on the UK government “to cease its intransigence and engage constructively with the new treaty”, arguing that the polling showed this position would command popular support. But there is no prospect of the world’s leading nuclear powers endorsing it. Jens Stoltenberg, the secretary general of Nato, said in November the treaty disregarded the realities of global security. “Giving up our deterrent without any guarantees that others will do the same is a dangerous option,” he said. “A world where Russia, China, North Korea and others have nuclear weapons, but Nato does not, is not a safer world.” Recent years have seen a gradual erosion of global nuclear controls, with the 1987 intermediate nuclear forces (INF) treaty, which kept nuclear missiles off European soil, allowed to expire in 2019 amid mutual recriminations from Russia and the US. The new strategic arms reduction treaty between the US and Russia, which limits each country to no more than 1,550 deployed nuclear warheads and 700 deployed missiles and bombers, is due to expire on 5 February – although Nato is calling on both sides to extend it following this week’s inauguration of Joe Biden as American president. The TPNW emerged following the creation of a UN working group in 2016. It was supported by 123 countries, with 38 voting against. The US, UK, France and Russia were all opposed, as was Israel, which is widely believed to possess nuclear weapons. China, India and Pakistan abstained. Countries that have ratified the agreement include Nigeria, Malaysia, Ireland, Malta, Thailand, Mexico, South Africa, Bangladesh, New Zealand, Vietnam and the Vatican City – although last autumn the US made a last-ditch lobbying attempt to try to convince countries to rescind their signatures. That effort failed, and in October Honduras became the 50th country to sign the document, which meant that it would gain legal force after a 90-day period. Rebecca Johnson, a veteran disarmament campaigner and a leading figure behind the development of the treaty, said: “This is an example of UN multilateralism in action. Britain needs to be at the table, taking the next steps towards ridding the world of nuclear weapons.” The Foreign Office said the UK was “committed to the long-term goal of a world without nuclear weapons”. A spokesperson added: “We firmly believe the best way to achieve this is through gradual multilateral disarmament.”