Britain's nuclear deterrent has been a contentious issue on the left for as long as it has existed. And it is not difficult to sympathise with the anti-nuclear argument. Fundamentally, no sane human being wants to live in a world where these weapons exist. And certainly nobody wants nuclear military facilities and nuclear weapons stationed anywhere near where they live.
But whatever the people of Britain made of the country's nuclear deterrent, the realities of the Cold War meant that there was a solid political consensus around the need to develop these capabilities. Those realities are long gone, however. And with them, it might seem, much of the argument in favour of the nuclear deterrent.
The so called 'Westminster parties', or to be precise, the leadership of the Conservatives and of Labour, have not moved on the issue. The Lib-Dems argued against renewing Trident in the run-up to the last general election, but as with most of their policies, they had to abandon their stance on that issue when they joined the coalition government. Today, the loudest voices against the nuclear deterrent are the Greens and the SNP. But while the Greens may poll higher in the national vote than the SNP in the coming election, it will most likely be the SNP MPs that will have most influence over the future of Trident.
So what should we do about Trident? Does the SNP argument against it stand up to scrutiny? The government to be formed after this election will face the decision on whether or not to renew it, and we must be clear about the downside, as well as the upside of any proposal to scale down or indeed axe the whole programme.
There are a number of reasons invoked against renewing Trident, and not just by the SNP. There is the moral case against having such weapons of mass destruction available. There is the question of leadership in the international effort to support the Non-Proliferation Treaty - the UK could take moral charge of the debate on non-proliferation if it were to unilaterally scale down its capabilities. And then there is the question of cost: in an age of austerity, do we really want to spend £100bn over 20 years on a 'just in case' white elephant weapon system? And this at a time when we are having to scale down our conventional military capacity to frankly embarrassing levels, and at a time when there are no obvious nuclear threats to our security, but there are quite a few obvious conventional and terror threats.
I do see these points. I also wished I could support the sentiment wholeheartedly. But I come from a security studies background, and the way geo-politics is going at the moment, unilateral disengagement is really not an attractive option.
During our lifetime we will see the world go through some very difficult challenges: from population explosions in countries which are unable to sustain them, to climate change, water shortages, to peak oil, to name but a few.
Geo-politically, we can see the emergence of a revanchist Russia seemingly committed to tearing up the rule-book of international order and cooperation. Their strategy in Georgia, in Ukraine, their support for regimes like that of Assad in Syria sadly places us not in a 21st Century global civil society framework of international relations, but a 19th Century balance of power situation of Russia vs NATO. For example, just recently Russia said it will target Dutch defence capabilities with its nuclear weapons if it joins the NATO missile defence system.
Meanwhile, the progress of nuclear talks with Shi'a Iran is still uncertain, while Sunni Pakistan is already a regional nuclear power, Jewish Israel can safely be assumed to possess nuclear weapons, and Sunni Saudi Arabia saying just the other day that they are considering starting their own nuclear programme. And according the International Atomic Energy Authority, the UN's nuclear watchdog, within our lifetime we will see the emergence of over a dozen so called 'virtual nuclear states'. That is states that have the technology, know-how, raw material and expertise to assemble atomic weapons in a very short space of time but will refrain from crossing that critical barrier until need be. Make no mistake: sooner or later, many of these countries will go to war to secure scarce resources and to protect themselves from perceived political and ideological threats. And in the current proliferation environment, there is no telling how long before nuclear weapons may be used again.
So I do believe that every party should make it an explicit election manifesto promise to do whatever they can to de-nuclearise not just the UK but all countries. But starting with the UK is simply to ignore the very serious situation beyond our shores. And yes, Trident is very expensive and the money could be used for better schools and hospitals. But the first duty of the state is the protection of the security of its citizens. And the tragic fact of the matter is that nuclear weapons do exist and they exist in an increasingly unstable and uncertain world. Trident is expensive, but it is only 0.1 GDP. And it does offer the ultimate insurance policy for our security. We may not like it. This is certainly not the ideal world we want to live in. But the truth of anti-proliferation is that starting it at home, in the UK, is just not a good way of going about it. The SNP may have political capital to gain by railing against the location of the Trident base in the Firth of Clyde, but the UK as a whole has much to lose if they win this argument.
Dr Azeem Ibrahim is an International Security Lecturer at the University of Chicago and a Research Professor at the Strategic Studies Institute US Army War College.