This is the year. 2014 will mark the historic referendum in which Scotland, yet again, votes whether or not to secede from the United Kingdom and go it alone. Having read Halting State, Charlie Stross‘ fantastic novel set in the nation of Scotland in 2018, there’s a whole realm of aesthetic and imagination and possibility associated with the prospects of an independent Edinburgh. Others are just as interested: Tyler Cowen makes one of the economic arguments against Scottish independence, and Tom Ricks asks all the questions, But part of my interest lies in more prosaic matters: namely, where do the nukes go?

Scotland’s defense policy would likely align much more closely with those of Norway and Denmark than with its southern neighbor. Between North Sea oil and Arctic issues, Holyrood’s posture and attention would be directed entirely upwards. And of all the realms in which nuclear weapons might not have such great utility (especially not as large submarine-borne countervalue weapons), the Arctic is probably #1. If NATO plays it cool and avoids major engagements, then a single brigade might just cut it. But otherwise that might be wishful thinking.

The Firth of Clyde is of major importance to the Royal Navy. But the shipbuilding contracts there are likely to depart along with UK forces. These could be repurposed by Scotland for new construction to augment its few unarmed fishery protection vessels (this, of course, depends on what Edinburgh is able to successfully wrest away from London). But more importantly, the Clyde is the heart of the British nuclear deterrent.

Right now, the UK’s four Vanguard-class Trident SSBNs are based at HM Naval Base Clyde at Faslane in the Clyde, with additional support coming from RNAD Coulport. And this is no abberration; Scotland has been critical to the UK deterrent from its inception. In 1963, when the Royal Navy was looking into acquiring Polaris from the United States, it drew up a short list of ten candidate sites for basing nuclear submarines. Of the ten, six were in Scotland. But what about the others? Would they play host to an atomic arsenal in the 21st century?

Malcolm Chalmers and William Walker, in their seminal “The United Kingdom, Nuclear Weapons, and the Scottish Question,” consider two of the four non-Scottish sites (the other two are dismissed without explanation). Devenport is possibility, though probably too close to built-up areas. Milford Haven is relatively well-suited, but the thorny issue of Welsh-ness comes into play, as Walker and Chalmers fear that Scottish independence might be accompanied by newly-stirred Welsh desires for the same. This probably rules out Cornwall, too. And with Wessex and Essex at each other’s throats…

But looking at a population density map of Great Britain, the situation actually appears somewhat manageable in terms of populated areas. As for deep harbors and soundings and the like, that’s a whole other kettle of fish. And whether it would be possible to have alternative warhead storage sites certified in time is unknown, but critical.

Walker, writing ten years later, dismissed the possibility of relocating the deterrent entirely, but also preserving it in Scotland (by some special accommodation) for 10-20 years until the current Vanguard boats reach the ends of their service lives. Somewhat fortunately, as Jeff Lewis puts it: “the UK government took the time-honored, if not particularly creative, route of commissioning an study of alternatives,” which will postpone a decision on whether to replace the Vanguard class or not until 2016, after the next general election.

In the meantime, we have Her Majesty’s Government’s Trident Alternatives Review, which essentially rules out any new nuclear weapons platform that would require a new warhead design on the grounds of cost (estimated at £8-10 billion, versus £4 billion for a new Trident warhead). While the executive summary does reference the Nonproliferation Treaty (NPT), it does not address the argument that wholly new warhead designs violate it. And as the Review concludes: “None of these alternative systems and postures offers the same degree of resilience as the current posture of Continuous at Sea Deterrence, nor could they guarantee a prompt response in all circumstances.” It wouldn’t be cheaper, either. Even if something-other-than-Trident (SOTT?) were to be the replacement, the Vanguard lifecycle means that two interim SSBNs would need to be produced anyways, all but ruling out any new systems. That is, of course, unless the UK were forced to divest itself of even Trident.

While many have asked where Whitehall would rebase the British nuclear deterrent should Scotland vote “aye,” few have looked at the possibility of Scotland retaining some of these weapons. Granted, the Scottish National Party (SNP) has firmly declared zero interest in Scottish nuclear weapons, but nevertheless, the same arguments being made to justify immediate European Union membership might theoretically be applied to the NPT. This IISS overview raises an interesting point; to wit:

The SNP does plan for Scotland to apply to join NATO. However, there is considerable uncertainty regarding its proposed membership of the EU. The White Paper argues that Scotland, as part of the UK, has been an EU member since 1973. It intends that Scotland would become a member in its own right immediately upon independence. It does not believe it should have to apply under Article 49 of the Treaty of the European Union, which covers normal enlargement processes. Rather, it proposes to enter immediately under Article 48, which provides for amendments to EU treaties. This would depend on the unanimous agreement of member states.

This is open to question. Officials from the European Commission, as well as member states, have sent conflicting signals as to whether Scotland would be expected to begin the membership process from scratch – which would be a major setback for the SNP.

If being a signatory to the Nonproliferation Treaty is a transitive membership, then an independent Scotland would be a de jure nuclear weapons state. So let’s see – is there a Vienna Convention for that? You bet your ass there is: the Vienna Convention on Succession of States in Respect of Treaties. It distinguishes, roughly, between post-colonial (“newly independent,” e.g., India) and replacement (“successor states,” e.g. post-Soviet Russia). Little is said of secession itself, in which a state produces two or more states, one of which will claim the mantle of successor. In the Scottish case, this would be the United Kingdom of England, Wales, and Northern Ireland. Succession procedures are fairly well-known. Russia took the Soviet Union’s seat on the UN Security Council, Soviet embassies became Russian embassies, international treaties with the Soviet Union became treaties with Russia. But it is on this last point that history proves nebulous.

The Cold War ended with thousands of nuclear weapons spread across the newly-independent states of Ukraine, Belarus, and Kazakhstan. They voluntarily returned the weapons on their territory to Russian control, and each individually acceded to the NPT. None tried to make the claim that they, too, had joined as nuclear weapons states. Kazakhstan perhaps would have had the best legal case. As home to the Semipalatinsk test site, a weapon was first detonated on Kazakh soil in 1947 – well before the NPT’s 1967 cutoff. But even despite last-minute, second thoughts from Ukrainian President Leonid Kuchma and other supporters, neither Kazakhstan nor Ukraine nor Belarus retained their arsenals. Comparing the three with Scotland is further complicated by the difference in delivery systems. All of the United Kingdom’s nuclear weapons are on SSBNs, which are a far more portable platform than ICBM silos, and would likely be withdrawn south of whatever maritime border is established between Scotland and the UK, regardless of Edinburgh’s wishes.

It is a certainty that neither London nor Edinburgh desire a Scottish nuclear deterrent (after all, such a deterrent would be used against…who, exactly?). As the SNP’s own platform states:

The SNP position on this is that the constitution should include an explicit ban on nuclear weapons being based on Scottish territory. This reinforces the SNP’s unshakable opposition to nuclear weapons, and that is the context in which we will debate NATO.

Alas, we almost certainly won’t be seeing William Wallace-class SSBNs on station in the North Sea or Highlander I (there can only be I) ICBMs in silos. Whether we’ll even continue to see Trident, though…