One of the Royal Navy's Trident-capable nuclear submarines, pictured off the HMNB Clyde ( In the final days of the Scottish referendum campaign, public and academic attention has naturally focused on the immediate and emotive ramifications of a potential “yes” vote—with the inevitable result that other outcomes (less prominent, but no less profound) have been neglected. This is particularly true in the case of the auxiliary debate about Scotland’s nuclear future, where the fate of the nuclear Trident missile-carrying submarine program looms predictably large and where equally significant consequences for nonproliferation have been correspondingly side-lined.

The governing pro-independence Scottish National Party aspires to a non-nuclear Scotland, and has pledged the expulsion of the Royal Navy’s ballistic missile submarine fleet from its home base at Faslane, located in western Scotland, by 2020. In addition to the constitutional upheaval it would cause, Scottish independence would require the rest of the United Kingdom (the so-called “rU.K.”) to rethink its status as a nuclear power. It is this question, in both its philosophical and practical implications, that has received much recent attention. There is, however, more to the nuclear debate than the possible demise of Trident. Regardless of how Scotland and the rU.K. eventually resolve their differences, a substantial challenge to safeguards against nuclear proliferation will arise. This will inevitably place additional strain on the International Atomic Energy Agency (IAEA) and the nonproliferation community as a whole.

The practical starting point is this: the United Kingdom is a nuclear weapons state and, under international law, a seceding Scotland could not become one even if it so desired. The Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which underpins the global nonproliferation regime, rests on a simple—though endlessly controversial—binary: a state party is either considered a nuclear weapons state, or it is not. Only five states enjoy the privileges of the former category: China, France, Russia, the United States, and the United Kingdom. No provision exists for the expansion of this group. A nuclear weapons state is defined in absolute terms as “one which has manufactured and exploded a nuclear weapon or other explosive device prior to 1 January 1967.” Scotland would thus be born as a non-nuclear weapons state and, if it were to become party to the NPT, would have to abide by IAEA safeguards.

Helpfully, the emergence of a new non-nuclear weapons state from a parent nuclear weapons state is not without precedent. The breakup of the Soviet Union provides comparable cases in the form of Ukraine, Belarus, and Kazakhstan. In 1991, the newly independent Ukraine found itself in possession of the third-largest nuclear arsenal in the world, after the United States and a territorially reduced Russia. After signing the Budapest Memorandum on Security Assurances in 1994, which transferred its nuclear arsenal to Russia, Ukraine joined the NPT as a non-nuclear weapons state. A standard safeguards agreement was then swiftly concluded with the IAEA, with an additional protocol granting the agency a broader investigatory remit that entered into force in 1998. In all likelihood, an independent Scotland would pursue the same course: a standard safeguards agreement almost certainly followed swiftly by an additional protocol negotiated directly with the IAEA. Such provisions would mean a new IAEA state-level evaluation for Scotland involving facilities inspections and material inventories. Unlike post-Soviet Kazakhstan, for example, Scotland has only limited civilian nuclear infrastructure to inspect since most of Britain’s fuel services facilities lie south of the Scottish-English border. It is also fortunate that the United Kingdom’s primary nuclear weapons facility, the Atomic Weapons Establishment, is located at Aldermaston, in southern England. In practical terms, there are therefore very few sites in Scotland that would require the application of IAEA safeguards. At least at a superficial level, the task appears straightforward.

The problem, however, is that nuclear proliferation is more than simply a technological process. Human expertise in the design, manufacture, deployment, and maintenance of nuclear weapons is as vital as the possession of the relevant materials. Scotland possesses a developed nuclear infrastructure and has access from within its citizenry to a body of nuclear expertise covering every conceivable aspect of a nuclear weapons program, from enrichment to delivery systems. This human capital forms the crux of the issue. What would become of the scientists, engineers and servicemen at Her Majesty’s Naval Base, Clyde? And what of the unnumbered Scots scattered across the United Kingdom working in high-security areas? There are hundreds of thousands of Britons living outside Scotland who might nevertheless conceive of themselves as Scottish. The 750,000 Scottish-born residents of England, at the very least, would have a strong case, as would those with other compelling hereditary ties. In fact, it would be near-impossible to disaggregate the multiple national identities that could be at play: the fluidity of British national identity is such that one can be London-born and London-raised while still considering oneself solely Scottish.

This fluidity becomes especially problematic under the terms of the NPT, which decrees that each member state agree “not to transfer to any recipient whatsoever nuclear weapons or other nuclear explosive devices or control over such weapons or explosive devices directly, or indirectly; and not in any way to assist, encourage, or induce any non-nuclear weapon State to manufacture or otherwise acquire nuclear weapons…” The notion of “assistance” presents the issue. The dissolution of the United Kingdom could conceivably constitute such assistance via a wholesale transfer of nuclear knowledge to the new Scotland. By way of abstraction, suppose evidence were to emerge that several hundred foreign nationals had been transferred to a nuclear weapons state for the purposes of working on a nuclear project. The individuals in question had privileged access to the highest level of classified technology and research, and had even designed and lead aspects of the program. In some cases the duration of the individuals’ stay lasted decades. If these scientists were to return to their country of origin, no matter how negligible that country’s technical capacity, the proliferation of such a vast amount of knowledge could not be ignored. In a world where dual citizenship—even with closely allied Commonwealth countries such as Canada—is sufficient to bar undergraduate engineering students from trivial (that is to say, unclassified) internships with BAE Systems, for instance, such a degree of information exposure would be intolerable. It would also have to be addressed in some form by the IAEA in designing safeguards against future proliferation.

This does not necessarily imply that an independent Scotland should be considered a grave proliferation risk. Independence, however, would without a doubt generate a cadre of suddenly unemployed Scots possessing firsthand knowledge of every relevant technical and research aspect of a highly developed nuclear weapons state with no immediate domestic outlet for those skills. In the world of proliferation, access to even a modicum of knowledge can be dangerous. Pakistan’s nuclear weapons program, for example, was kick-started by access to information and technology on so relatively trivial a scale that a single individual, Abdul Qadeer Khan, can be held largely responsible for its eventual development. Troublingly, the amount of information possessed by citizens of an independent Scotland would be immeasurably vaster—and far more substantively specific to nuclear weapons design—than Khan's ever was.

The challenges raised herein are not necessarily of recent provenance—such tensions have arguably existed in latent form within the nonproliferation regime since its inception. A Scottish “yes” vote to seek independence would, however, bring these issues very rapidly to the fore. Regardless of the outcome on Thursday, the nuclear safeguards community should move immediately to address itself to the questions provoked by the prospect of secession in nuclear weapons states in order to secure future nonproliferation efforts.