It's not every day you find yourself lying on a freezing military runway at 7 o'clock in the morning. I don’t take breaking the law lightly, so why did we decide to climb a three-metre barbed-wire fence to break into the Kleine Brogel Air Base in Belgium where the country stores US bombs?

There are 15,000 nuclear bombs still in circulation in the world and about 20 nuclear bombs are still present at the Kleine Brogel military base. The UK’s own arsenal is an estimated 215 nuclear warheads, each of which is far more deadly than the first nuclear bomb that destroyed Hiroshima.

Whilst figures will not muster much emotional response from many of us, perhaps the human cost of nuclear warfare will. This is a quote from Fujio Torikoshi, 86, who survived Hiroshima:

“I was told that I had until about age 20 to live. Yet here I am seven decades later, aged 86. All I want to do is forget, but the prominent keloid scar on my neck is a daily reminder of the atomic bomb. We cannot continue to sacrifice precious lives to warfare. All I can do is pray – earnestly, relentlessly – for world peace.”

I have been a peace activist since I joined the Campaign for Nuclear Disarmament at the age of 16 and was inspired by the Greenham Common Women’s Peace Camp which was close to my home and which I visited as a teenager. My reasons for supporting unilateral nuclear disarmament have always been consistent: I find it fundamentally unethical for any state to hold hideously destructive weapons and threaten to use them merely to reinforce their power in the world.

Iran parliament reacts after Trump's withdrawal from nuclear deal Show all 10 1 /10 Iran parliament reacts after Trump's withdrawal from nuclear deal Iran parliament reacts after Trump's withdrawal from nuclear deal Iranian MPs burnt a US flag in parliament after Donald Trump announced America's withdrawal from the nuclear deal. AFP/Islamic Consultative Assembly News Agency Iran parliament reacts after Trump's withdrawal from nuclear deal US President Donald Trump displays a presidential memorandum after announcing his intent to withdraw from the JCPOA Iran nuclear agreement in the Diplomatic Room at the White House. Reuters Iran parliament reacts after Trump's withdrawal from nuclear deal Some Iranian MPs reacted after Trumps decision by shouting 'death to America'. AFP/Islamic Consultative Assembly News Agency Iran parliament reacts after Trump's withdrawal from nuclear deal Iranian lawmakers prepare to burn two pieces of papers representing the US flag and the nuclear deal. AP Iran parliament reacts after Trump's withdrawal from nuclear deal Iran said it will hold talks with signatories to the nuclear deal after Trump's decision to withdraw from the accord, which it branded "psychological warfare". AFP/Islamic Consultative Assembly News Agency Iran parliament reacts after Trump's withdrawal from nuclear deal Several Iranian MPs stood chanting in the Tehran parliament. AFP/Islamic Consultative Assembly News Agency Iran parliament reacts after Trump's withdrawal from nuclear deal Iranian MPs burning a US flag AFP/Islamic Consultative Assembly News Agency Iran parliament reacts after Trump's withdrawal from nuclear deal President Hassan Rouhani addressed the nation in a televised speech in Tehran. He said he'd send his foreign minister to negotiate with countries remaining in the nuclear deal after Trump's decision to pull America from the deal, warning he otherwise would restart enriching uranium "in the next weeks." Iranian Presidency Office via AP Iran parliament reacts after Trump's withdrawal from nuclear deal Iran's press condemned Trump's withdrawal from a multi-party nuclear deal but was divided over whether Tehran should react with patience or withdraw itself. AFP Iran parliament reacts after Trump's withdrawal from nuclear deal Trump announced the US withdrawal from what he called the "defective" multinational nuclear deal with Iran, and said Washington would reinstate sanctions against the Islamic republic. AFP/Getty

But even if you believe that multilateral disarmament is the best approach – as many of our politicians claim to – then you do at least need to act on that belief. The European Parliament passed a motion in October 2016 in support of the UN-sponsored Treaty on the Prohibition of Nuclear Weapons, which has already been signed by EU member Austria and 20 other countries, while 50 more are on their way to signing. This is multilateral disarmament in action, supported by a campaign that was rewarded with the 2017 Nobel Peace Prize. So why aren't our politicians ensuring that the UK is signed up? Why is there so little debate about the Treaty that most British people have never even heard of it?

Aside from the deeply unethical nature of a nuclear security policy, the big world powers are behind the times. The modern-day threats come from asymmetric and cyber warfare for which nuclear weapons have no relevance. With Russian attempts to destabilise our democracy and four people I represent in the South West poisoned with nerve agent by Russian agents – one of whom sadly died – it is clear that our so-called defence policy is wholly misguided. So it has never been more urgent to review our approach to defence policy. The decision by president Trump to withdraw from the Intermediate-Range Nuclear Forces Treaty, risking a new arms race, just adds to the urgency.

The real debate we hope to provoke through this action at the air base is about what a genuine 21st century security policy would look like. A positive contribution to this debate is already being made by Rethinking Security , a network of organisations, academics and activists working together for security based on justice, cooperation and sustainability. They are asking what really makes us safe in the world, and how we can counter the power of the arms trade to ensure that we spend as much money on peace-building as on buying weapons.

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The ludicrous posturing of our defence secretary Gavin Williamson, with his suggestions about establishing new military bases for Global Britain in the Caribbean and the Far East is designed to shore up his position in his own party rather than providing peace and security for the country. In a democracy it is our right to debate how our taxes are spent to ensure our safety and to underpin peace in the world.

If our action at the base this week has helped to focus attention on the real possibility of nuclear disarmament and a defence policy focusing on genuine security, then the cold and uncomfortable morning I spent there was well worth it.