At the SNP October conference the leadership hope to get acceptance – as a fact – of the claim that Scotland will inherit its treaty obligations with Nato, and endorsement for a policy change that will permit an independent Scotland with an SNP Government to remain within Nato providing the UK Government accepts that nuclear weapons will be removed from Scotland as soon as possible.

This would result, de facto, in the rest of the UK (RUK) losing its nuclear deterrent, and Nato losing a significant part of its European nuclear deterrent capacity.

The claim that an independent Scotland will inherit Nato treaty obligations is disputable under Article 9 of Vienna Convention interpretations. If it does inherit such obligations, how can it unilaterally repudiate them and make its continued membership of Nato conditional on Trident being removed from Scotland, and RUK losing its nuclear deterrent? Why would the UK (and Nato) regard Scotland's membership as desirable under such circumstances?

The time frame over which this will take place, important dates within it and the possible context at different points in that time frame are crucial to possible outcomes.

The period from now until October 18, 2012 (the SNP party conference at Perth) is significant because the debate the SNP wanted to keep in house and on hold until the conference is now in full voice, with a cross-party, cross-interest coalition of opposition stating their positions and securing wide debate and coverage ("Divisions grow within SNP over Nato policy U-turn", The Herald, August 27).

The First Minister, Alex Salmond, and the party's chief strategist, defence spokesman and party leader at Westminster, Angus Robertson, will now face a highly informed group of delegates, many mandated by branch resolutions on Nato membership. What was intended to be one topic among many will now be a principal one.

Other dates in the time frame are significant for the following reasons:

l Late 2013 – launch of detailed policy papers on the shape of an independent Scotland by the Scottish Government. In effect, this will embrace the key negotiating objectives for the Scottish Government across a wide range of issues if they win a Yes vote in 2014.

l Autumn 2014 – the independence referendum. Following a Yes vote, negotiations will commence almost immediately on the terms of independence, including the crucial defence issues. If the outcome is No, or on a two-question referendum, a devo-max outcome, what follows is anybody's guess.

l May 2015 – latest date for UK General Election. A change of government at this point early in the negotiations over independence would have major significance for the negotiating agenda: the idea that there would be a seamless continuation is untenable, and a new Government could repudiate provisional agreements already reached and introduce new items to a still live negotiating agenda. It is highly unlikely they would repudiate a fully-completed and signed agreement.

l May 2016 – Scottish Parliamentary elections. At this point, negotiations on the independence of Scotland could be complete (unlikely, in my view), near-complete (a possibility) or have a long way to go, especially on defence-related issues (highly likely). The implications of a change in the power balance at Holyrood or even a change of Government are enormous and far-reaching.

Peter Curran,

1B Main Street,

Kirkliston,

West Lothian.

It is entirely proper that Isobel Lindsay should ask what military threat Scotland faces that we need to join Nato (Letters, August 27 ).

In the real world, it is inconceivable that any member state of the EU should be invaded by any other country within the EU, and even less likely by a state outwith the Union.

Apart from such military considerations, there is another and more fundamental aspect to the proposed membership of Nato: the moral implications. Like many others, I was attracted to the SNP because it maintained a principled opposition to Britain's nuclear WMD, the so-called "independent British deterrent". In joining Nato, the SNP is proposing that Scotland become a member of an alliance which supports the deployment and use of American nuclear weapons.

The first Nato Secretary General, Lord Ismay, stated in 1949 that the organisation's goal was "to keep the Russians out, the Americans in and the Germans down". It is thus firmly rooted in the demonology of deterrence. But there never was a Soviet masterplan to attack Britain. What the Soviet government did have, was an obsessive fear of an American nuclear first strike. This fear existed because first strike use was, and still is, the official policy of America, and of her surrogate organisation, Nato.

Because this is the case, it would be an abject betrayal for the SNP to abandon its former principled opposition to Nato and now give support to an organisation which has a policy of first use of nuclear WMD – the very class of weaponry the SNP rightly opposes in Trident.

Brian Quayle,

2 Hyndland Avenue,

Glasgow.