On Sunday, the Norwegian Nobel Committee will award the 2017 Nobel Peace Prize to the International Campaign to Abolish Nuclear Weapons (ICAN) "for its work to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons and for its ground-breaking efforts to achieve a treaty-based prohibition of such weapons."

Britain has a longstanding history of support for multilateral disarmament, which is why our government’s decision to snub Norway and the many British and international citizens and organisations that have worked with ICAN over the past decade is so infuriating.

ICAN has brought together survivors of nuclear weapons use, production and testing, and made a powerful case that nuclear weapons need to be banned as a vital next step to eliminating existing arsenals.

We support the Treaty on the Prohibition of Nuclear Weapons, which was adopted by the UN in July and opened for signature by the UN Secretary-General in September 2017. We consider this Treaty to be a vital new addition to international law that reinforces and strengthens the nuclear non-proliferation regime as a whole.

As leaders of political parties in Britain, we have pledged to press the government to sign, ratify and do everything in its power to enable this important multilateral treaty to enter into force without delay, as an essential step towards the realisation of nuclear weapons free world.

The dangers of relying on nuclear weapons for deterrence have never been as clear as today, when we see leaders like Donald Trump and Kim Jong-un exchanging irresponsible nuclear threats and insults while enjoying the power to launch US and North Korean nuclear weapons across the Asia-Pacific region.

Now, more than ever, we can see that there are no safe hands for these weapons of mass destruction.

While boycotting the UN's multilateral disarmament talks these past two years, the UK government has greatly increased its spending on the Trident replacement programme, while denying necessary funding to equip Britain's conventional defence services and simultaneously embarking on a programme of sustained austerity, causing hardship to the most vulnerable members of society.

Trident renewal involves the proposed siting of weapons of mass destruction in Scotland for decades to come – against the wishes of the Scottish Parliament, a majority of Scotland’s MPs, churches and civic society.

Government ministers say they support multilateral disarmament – all we’re saying is that they should stick to their word.

In the early 1980s, Sir Henry Leach, First Sea Lord, opposed Trident nuclear weapons, which he described as "useless" and "a cuckoo in the naval nest". Many eminent generals, admirals and defence experts have agreed with this assessment, which is even truer today.

Yet, despite the Cold War ending in 1991, successive British governments have squandered hundreds of billions on retaining nuclear status if not security. We can't carry on with such reckless expenditure on an obsolete type of weapon unfit for the 21st century.

Nuclear weapons, and activities such as their use, testing, development, manufacture, deployment and acquisition, are prohibited by the UN Treaty, and it is only a matter of time before their use is recognised as a crime against humanity and their possession becomes unacceptable for any civilised nation to continue with. This is what happened when treaties prohibiting biological and chemical weapons came into force.

Most importantly, the UN Nuclear Prohibition Treaty offers Britain a sensible way out of the nuclear dead end. It provides a process by which a nuclear-armed country like Britain can sign as an initial step towards compliance, and then negotiate and undertake an agreed practical timetable to dismantle and eliminate its nuclear weapons as safely and securely as possible. Existing weapons would need to be immediately taken off active deployment. After that is done, the Treaty allows for a transition period from nuclear-armed to nuclear free. This would enable Britain to save defence jobs, reskill our workers and diversify relevant industries to play more appropriate roles for our future security and economic independence.

We urge the government to sign the Treaty on the Prohibition of Nuclear Weapons without further delay and stop wasting public money on weapons of mass destruction that threaten human survival and could never rationally, morally or legally be fired.