Hillary Clinton was careful to say, as they are all careful to say, that she has no vote in Scotland's referendum.

Well, who would have thought? Like her former boss Barack Obama, the erstwhile US Secretary of State certainly didn't want to sound as though she was interfering in anyone's democracy. Since the BBC persists in asking the question, however, the apparently coy answers keep on coming.

In this instance, Mrs Clinton told Newsnight's Jeremy Paxman that "I would hate to have you lose Scotland. I hope that it doesn't happen, but I don't have a vote in Scotland. But I would hope it doesn't happen. I would think it would be a loss for both sides but, again, I don't have a vote".

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Credit where credit's due: Mrs Clinton seemed to have a firm grasp of the meaning of "you" in such a context. To be parochial, I'm pretty sure she wasn't addressing me, or numbers of readers I otherwise think of as you. I'm also prepared to bet that what she knows about Scotland exceeds only slightly the extent to which she cares. Lockerbie aside, it's not a country whose name comes up often in the life of a US Secretary of State.

There is not much doubt, either, that the London Government has been working hard to extract remarks in favour of the Union from passing international personages. Given reports that David Cameron even attempted to cajole the Queen into uttering an anti-independence opinion in her recent speech to Parliament, Mrs Clinton probably offered up the minimum required, doubtless after weighing possible effects on the Scottish diaspora in the US.

In any case, the facade of American neutrality over independence, such as it was, has cracked. The first instinct of Mrs Clinton, and to a lesser extent Mr Obama, is to lend support to the Labour Party while ensuring that a satellite does not wobble. Given world affairs, little local difficulties in a US sphere of influence are not to be encouraged. Ironically enough, Unionist eurosceptics can expect much the same treatment if Mr Cameron's party attempts to take the United Kingdom out of the European Union. But that bit of fun will keep.

It is safe to say, meanwhile, that a few words from Mrs Clinton or Mr Obama will not sway too many votes in September. At most, they are liable to provoke mild umbrage among those Scots who know exactly how Americans react to advice from interfering foreigners. "How will this play in Washington?" is not a question you are likely to hear at the polling stations.

These "top-level interventions" from Americans must be a little galling, nevertheless, for Alex Salmond. The First Minister has gone to some lengths to assure the US of Scotland's undying friendship. He has steered his party into a commitment to Nato. Given the near universal assumption elsewhere, yet to be tested, that the SNP will govern an independent country, Mr Salmond's offer of two allies for the price of one surely ought to have done the trick.

At Mrs Clinton's old State Department workplace in Washington's Foggy Bottom, and over at the Pentagon, they don't think that way. The UK's essential worth as a trusted ally is these days four-fold: handy special forces, GCHQ, a useful flag, and nuclear weapons. The remainder of Britain's diminished military might is not rated highly. The idea that Trident might become a problem catches the eye, however. Like Mrs Clinton, the military-industrial types will certainly hope that Whitehall doesn't "lose" Scotland.

The SNP's promise that it will get rid of the submarines should it form the government of an independent country is, we are told repeatedly, non-negotiable. I take the party and its leadership at their word. Timing, with the issue of safety paramount, might be another matter, but that too makes sense, however urgent the desire to be rid of the damnable things. Managing the transition to a non-nuclear Scotland while negotiating membership of Nato will require a good deal of finesse, perhaps enough to make people wonder if the treaty organisation is worth the bother. But no-one should doubt the SNP's seriousness.

That being so, someone should tell Whitehall. As the referendum draws nearer, and as the polls narrow, the Ministry of Defence and Coalition ministers persist in pretending that they have no contingency plans. Mad talk of annexations and the like has subsided, but billions are still being spent on schemes to "renew" the UK deterrent. SNP politicians continue to insist that the boats are going, yet the London government prepares to extend a semi-secret agreement with the Americans that has, or might have, Britain's soon-to-be-homeless nuclear force at its heart.

A Freedom of Information request by the campaigners at the Nuclear Information Service shows that the rarely-discussed Mutual Defence Agreement (MDA) will shortly acquire a new chapter. First established in 1958, this deal lays bare the myth that the UK deterrent is in any sense independent. In its latest incarnation it is expected to deepen "co-operation" between Britain and America in the design and development of a new generation of what the world needs least: a new generation of nuclear warheads. In any proper sense, it inaugurates a fresh wave of proliferation.

In one document obtained by the Nuclear Information Service, indeed, there are references to an "enhanced collaboration" between the two countries on "nuclear explosive package design and certification", on "maintenance of existing stockpiles", and finally on the "possible development of safer, more secure, warheads". Set aside the last and most comically bizarre of these notions. Whitehall is behaving as though nothing could affect its symbiotic relationship with the Pentagon. Yet unless the Trident boats find refuge in the US, they have no home, for now, but the Clyde. Should you decide to vote No in September, therefore, you will ensure that Scotland remains a repository for weapons of mass destruction for a very long time. When it comes to nuclear disarmament, after all, the MDA is better proof of real intent than all of Mr Obama's fine words.

Should you vote Yes to independence in the hope of a nuclear-free Scotland, however, it might be wise to understand what lies ahead. The military men are drawing up their latest special relationship agreement serenely confident that this small country will not interfere. London truly has no intention of quitting the Clyde. At minimum, this will place Trident at the heart of independent negotiations and guarantee that those negotiations will be anything but easy.

That will make them all the more worthwhile. As has been remarked often enough, an independent Scotland would do everyone in these islands a favour by bringing a decades-old issue to a head. As Iraq tumbles into chaos, as the usual mouthpieces in the UK agitate for another round of bloody "liberal intervention" to retrieve the reputations they lost last time around, the farce of a special relationship needs to be exposed.

You could put it otherwise. In September, Scotland has the chance to become independent of a state that has enjoyed no real independence of its own for a very long time. Mrs Clinton would still think all concerned special, I'm sure.