Much has been made, and quite rightly, about the financial uncertainties for the Scots attached to an independence vote.

But if there is a Yes vote the financial pressures on the UK’s nuclear weapons programme will also bite hard, plunging its future into uncertainty.

Experience so far in the referendum campaign amply demonstrates the inability of the collective Westminster-Whitehall (WW) bubble to accurately assess risk, probability and impact.

As I outlined in a previous post for Open Democracy, Trident will become the subject of negotiation along with other core issues such as currency, the handling of debt and membership of the EU and NATO.

But the bases at Faslane and Coulport will need to move, and within a similar timescale to the introduction of the new submarines.

Even assuming that the political obstacles can be overcome, capital spend on the move will hit at the same point in the cycle as the construction of the submarines, sending costs spiraling.

Trident’s medium term home? Georgia, USA

With any move south of the border the renewal programme would take up well over half the current MoD’s equipment spend throughout the 2020s (it is already set to eat up a third of that budget over this period).

But this is only one half of the double-whammy. The other is that this would happen just when public spending would need to reduce by around 8% as a result of the tax-take from Scotland being removed.

For most government departments, whose spend is relative to the population they serve, this would not be such a big deal beyond the bureaucratic challenge of institutional change.

But the Ministry of Defence will retain just about the same commitments as they have today, and cuts they would have to bear would follow on from major cuts experienced over the last five years.

There is a cost to the rest of the defence establishment beyond which even die-hard pro-nuclear advocates would not tread. Without Faslane, the UK’s only alternative would be to base its Trident submarines at the US’s Kings Bay Trident port on Georgia’s Atlantic coast.

The military community discussing this possibility at present refer to it as a temporary measure, but the political and budgetary costs may force them to consider it a permanent proposition.

But what sort of symbol would that send about Britain’s dependency upon the United States and its capability? It would make a mockery of the claim that they system is operationally independent.

For any member of the public or rational defence planner in London, Scottish independence would surely mean a radical reassessment of Trident.

A new impetus towards global nuclear disarmament?

Any such reassessment, if it leads to disarmament, could be a big shot in the arm for the essential but deeply-troubled global non-proliferation regime upon which we all depend for stability and survival. So far 2014 has been a disastrous year.

Things looked promising in the heady days of 2010, when the US and Russia signed their new START treaty further limiting the numbers of warheads, missiles and bombers, and the NPT Review Conference agreed a comprehensive action plan to pursue disarmament and non-proliferation.

But the rot had already set into any optimism for further progress years before President Viktor Yanukovych was chased out of Kiev at the beginning of this year.

With Russia’s annexation of Crimea, the civil war in eastern Ukraine (now becalmed if not quite over under a peace process), and other major disagreements over missile defence, NATO membership and influence across eastern Europe and the Middle East, the nuclear weapon states are showing no prospects of living up to the cautious agenda they signed up to in 2010.

This leaves next year’s NPT Review Conference and the broader non-proliferation regime in limbo.

Iran hanging in the balance

It also adds a wild card to negotiations with Iran that reopen this Thursday, the same day as the referendum vote.

Just as the Americans and Europeans were hopeful of breakthrough on Iran’s nuclear programme before the deadline in November (though there are still big differences between the negotiating positions), the fragile sanctions coalition could be breaking apart before our eyes.

The Russians are already talking about major deals with Iran that the Americans consider bust the sanctions. If they sense alternatives opening up, it seems highly unlikely that hardliners in Tehran will countenance Rouhani agreeing to tight constraints on the programme. This one silver lining in the dark and foreboding international nuclear proliferation skies hangs in the balance.

If an independent Scotland were to force a rethink on Trident renewal it would be crucial for both governments to see how their choices could best influence this broader context.

If there is a possibility of an established nuclear weapon state taking its arsenal off patrol this must be used to maximum leverage within the broader international diplomatic game to win real moves in a positive direction by other states. This will be an important opportunity for leadership.

In the event of a No

But what of the impact of the only other likely alternative, a close no vote? In this circumstance we are likely to see devolution of many more powers not only in Scotland, but also other parts of the union.

The general assumption within the WW bubble will be that this will not directly affect the trappings of statehood, in particular foreign policy and defence and thereby the nuclear deterrent. There are a number of distinct dangers to this attitude that could reflect more complacency piled on the previous.

When it reported back in July, the Trident Commission, co-chaired by Malcolm Rifkind, Des Browne and Menzies Campbell, pointed to the pressing need for Britain to reconsider its strategy and more effectively lead on achieving multilateral disarmament measures.

There is no room for business as usual whilst strategic international relations deteriorate and the non-proliferation regime faces severe challenges of confidence.

And there is no solution to the contradiction between renewing Trident like-for-like and positively contributing to a stronger non-proliferation regime.

Caution advised – is this a smart way to spend £30 billion?

But back at home our political leaders would be well-advised to be cautious in making their assumptions about London retaining unambiguous control over the existing nuclear weapon infrastructure.

After the referendum it is now clear the nature of the constitutional settlement will change, and could remain fluid and uncertain for some time to come. Demands for change can only grow throughout the union. London may in future struggle to hold the line and prevent further slide towards a break-up of the union as devolution develops.

A close no vote could in the long run simply spell a stay of execution, unless the government more effectively tackles the centrifugal forces driving the home nations apart.

This will need them to go beyond the devolution of certain powers, and radically change the relationship between the WW bubble and the people of Britain.

And Trident has already shown itself to be a significant part of that legitimacy deficit. It is not only the Scots who are sceptical about spending £30bn over the next two decades on the renewal of our nuclear weapons.

If they succeed in convincing the Scots to stay in for now, those interested in saving the union in the longer run may yet come to see Trident and its bases in Scotland as an important political liability that we can ill afford to keep.

Paul Ingram has been the Executive Director for the British American Security Information Council (BASIC) since 2007. BASIC works in the US, UK, Europe and the Middle East to promote global nuclear disarmament and a transformation in strategic relationships using a dialogue approach.

He was also until recently a talk show host on state Iranian TV promoting alternative perspectives on strategic matters, and taught British senior civil servants leadership skills.

Previously Paul was a Green Party councillor in Oxford and co-Leader of Oxford City Council (2000-2002) and a member of the Stop the War Coalition Steering Group (2002-2006).