The respected think tank Royal United Services Institute (RUSI) last week released a report on the future of Trident.

Authoritative and largely stripped of the hyperbolised cynicism of many recent defence reports, it nonetheless concluded what many of us already knew: that after a Yes vote, Trident could indeed be moved from Scotland, and that suggestions of a £25 billion relocation bill are fatuous. The report suggests instead a bill nearer £3bn.

Significantly, the report's authors raised questions over the Scottish Government's aspiration - if there is a Yes vote - to remove Trident from Scotland by 2020. Better, they say, to wait until 2028. This would give the UK Government time to develop another nuclear warhead storage and handling facility (thus recreating what Coulport currently does); it would also coincide with the entry into service of the UK's next generation of nuclear-armed submarines.

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The day after the report's publication, its authors presented their thesis to a public audience in Edinburgh. In responding to audience questions, the issue of "reasonableness" featured frequently. The SNP-led Scottish Government's stated timeframe for evicting Trident, they argued, isn't based upon technical or logistical considerations but political ones; it isn't reasonable to allow politicking to drive such a serious process. If the Scottish Government really is committed to the safe, responsible relocation of the UK's nuclear warheads, then it must allow a longer relocation process. A refusal to do so might rush the process, thus heightening the very "nuclear dangers" that the SNP is so critical of.

These are strong arguments and the underlying message was clear: if it does come to negotiating Trident's future, the Scottish Government must be reasonable. However, in reflecting upon these assertions, we might point out that "reasonableness" surely cuts both ways? There is a palpable expectation within the UK establishment that in the event of a Yes vote, Edinburgh should "play ball" with London's concerns on Trident. I have seen or read nothing which concedes that London should acknowledge Scotland's concerns.

Many Scots will doubtless bristle at the inference that "reasonableness" on Scotland's part equates to it effectively privileging London's wishes on Trident. Given that the wider Yes campaign generally supports the Scottish Government's Trident eviction aspirations as declared in its white paper, a Yes vote could legitimately be seen as giving the Scottish government a strong democratic mandate to act on those aspirations. It could also be argued that the UK would be violating the terms of the nuclear Non-Proliferation Treaty by building new facilities in England to rehouse Trident; some might question whether a newly independent Scotland would want to begin its sovereign life by being complicit in such a transgression.

In fact, there is nothing to suggest that the Scottish Government will act "unreasonably" on Trident after a Yes vote. The SNP has set out its longstanding opposition to nuclear weapons clearly and legitimately in its white paper. It has articulated a preferred 2020 exit deadline for Trident but has done so in a way which demonstrates that leeway may be possible. We should note also that it will almost certainly not just be SNP figures who would negotiate Trident on Scotland's behalf after a Yes vote. It would be an all-party Scottish delegation which would meet with representatives of the UK Government.

For now, it is left to Scotland's voters to decide whether this much-speculated negotiation will come about. One thing is clear; if there is a Yes vote, the Scottish Government will have some hard thinking to do. Hanging over everything will be the question of how far - if at all - it should concede to London's wishes. Would it be worth possibly souring Scottish-UK secession negotiations - and possibly damaging Scotland's chances of securing optimal gains during them - by insisting that the UK nuclear force is moved from Scotland sooner than London would like? But if concessions are made which offend the Scottish public, what impact would that have? Where should the line be drawn between principle and pragmatism?

Of course, speculating about the optimal timescale for relocating Trident to England assumes that Trident has a future in England. The RUSI report is cautious about this prospect. It suggests a site on the Fal estuary, just north of Falmouth, as the optimal venue for rehousing the UK's nuclear warheads but admits that this would be a "very unpopular" move, with myriad planning, safety and political problems to overcome. Falmouth's tourist board, conservationists and MPs are already talking stridently about why the area will not play host to nuclear weapons. The brewing political firestorm will be greatly exacerbated if - as is likely - the MoD has to loosen its safety parameters as those which pertain to Coulport cannot be matched at Falmouth.

A Yes vote will be the catalyst to these discussions but in the event of such a vote, the big question may not be how quickly Trident can be relocated to England, but whether it can be relocated at all.