IS the SNP's expected change of policy on Nato membership a sign of weakness, of cynical political trimming – or of strength, of mature adaptability?

The answer depends on whether Nato membership would require nuclear weapons to remain based in the territory of an independent Scotland. It would be very surprising if the SNP decided that it was, after all, quite relaxed about maintaining the nuclear mini-armada on the Clyde.

Of course it would be awkward for a newly independent Scotland, and a new member of Nato, to insist that the weapons had to go. But awkwardness is nothing in politics; just about every major decision a national government makes is awkward in one way or another.

It would be quite feasible and credible for Scotland to be in Nato but also to be a nuclear weapon-free zone. After all, Norway is already in exactly that position. Several other countries find it acceptable to be members of an organisation that has a huge nuclear arsenal yet insist on having no nuclear weapons on their own land.

Looking at it from Nato's perspective, I think the organisation would be concerned if an independent Scotland were NOT a member, nuclear weapons or not. After all the treaty is supposedly all about the North Atlantic (despite its current activities in far away Afghanistan) and few countries can claim a more direct geographic and strategic interest in the North Atlantic than Scotland. A Nato without Scotland would be a much weakened Nato.

The other factor to consider is that Nato is a loose and large alliance. Turkey has been a member since 1952, and this has not caused any embarrassment or distress – quite the opposite, in fact – despite the fact that Turkey is still (disgracefully) not regarded as fit to be a member of the EU.

And look at the French relationship with Nato. The French have been in the organisation from the very start (in 1949) but they have hardly been steadfast members. France's strongest post-war leader, Charles de Gaulle, angrily resented what he regarded as the American domination of the alliance to such an extent that at one stage he evicted all Nato personnel from France. Nato responded by moving its headquarters from France to Belgium.

But de Gaulle's peevish and drastic action did not entail France's expulsion from Nato, which has always been pragmatic and flexible. For many years France managed to maintain a "half-in half-out" status.

So I reckon it is perfectly feasible for Scotland to be a member of Nato without the nuclear facilities at Coulport and Faslane. There remains, however, the trickier question about how such a sudden reversal of a long-standing policy looks politically.

It isn't necessarily duplicitous if a serious political party undertakes major changes of direction. Members of other parties who accuse the SNP of duplicity should look at changes their own parties have made over the years.

Despite the sorrow, not to say horror, that the move prompted among many activists, in 1995 the Labour Party had the guts to drop its longstanding commitment to "common ownership of the means of production, distribution and exchange". Little harm ensued from this ditching of a cherished policy. Some thought the party had sold its soul, yet two years later it achieved its greatest ever electoral victory, and it went on to be endorsed by the British people in two further general elections. So much for the need to ring-fence "unassailable" policies.

No political party can stay the same for ever. Shedding policies that are dear to many members can be painful and can smack of expediency, but ultimately, if perhaps sadly, the massed ranks of electors are more important than the members.

The one thing that the SNP will have to watch is that it does not change too much too quickly, or it might gain a reputation for expediency. But expediency is nothing like as bad or dangerous as duplicity, and this proposed change of tack on Nato membership is certainly not duplicitous.