Eddie Barnes: Trident is just one reason why an independent Scotland's place in the EU would be far from guaranteed

HOW will it work, Mr Salmond? How? Since his victory three weeks ago, which has guaranteed the prospect of a referendum on independence, the newly re-elected First Minister has been urged to make clear how his plans will function.

On Monday, Mr Salmond declared how, these days, nations were interdependent with one another: "No man, no country, is truly isolated or separate. We are all part of a whole." The implication of this is that it is that same whole which will play a role in deciding how an independent Scotland would be formed.

The SNP has already acknowledged this with its idea of a "confederal" United Kingdom. The shape of a future independent Scotland would emerge through the UK-wide negotiations which would set the ground rules for the new confederation.

But to assume that Scottish independence would be something that could be sorted out between London and Edinburgh alone is also too parochial a view. There is the small matter of 27 European Union nations, for example. The widespread view, enshrined in international law, is that those countries would have a moral and legal duty to accept Scottish self-determination and EU membership. But, say EU officials privately, it's not as if there's a rule book codifying all this. Instead, it would all boil down to politics.

For example, Spain may be one country not entirely happy with Scottish secession (what chance the Basques describing it as evidence of a "European Spring"?). So, ask EU officials, might they threaten to withhold their support for Scotland's EU entry, unless Scotland offers, say, a deal on fishing access in the North Sea? One Brussels-based official notes that Scottish negotiators may find themselves spending a lot of time on the Madrid shuttle.

And then there is perhaps the biggest issue of all: Faslane. The Clyde site is widely seen as the only place to base nuclear subs in the British Isles, so a refusal by the Scots to keep them there could place London's nuclear deterrent in doubt. What might the rest of the EU, or indeed Britain's allies in Nato, think about that?

In a study into this issue written in 2002, Professor William Walker of St Andrew's University speculated that EU nations, fearing an unstable resolution, might use the bait of EU membership to persuade Scotland to keep the subs in Faslane. As for Washington's attitude, the US would urge the Scots to accept a compromise "involving an extension of basing rights". Ironically, Prof Walker noted that London may end up lobbying for Scottish membership of the EU, again in the hope of securing a deal with the Scots on the subs.

What would independence look like? Who can say? In Mr Salmond's interdependent world, the answer lies partly with him, but also in foreign capitals, in competing national interests and in the judgment calls of leaders often faced with a choice of two evils.