Issues of national defence and strategic policy have not traditionally rested easily within the SNP.

The party in the past has been left trying to balance two very different, in many ways contradictory constituencies. There is the passionate anti-nuclear and anti-NATO community on the Left of the party, which for years held significant sway over the SNP’s positioning.

Determined to make an international statement in favour of unilateral nuclear disarmament, this group supported independence as a way to force the UK to scrap its Trident missile system. On the other hand, the population of Scotland generally has not shown itself so preoccupied with issues of nuclear disarmament.

While there is conflicting data about whether the Scottish population supports the maintenance of the UK’s independent nuclear deterrent, a clear majority supports continuing membership of NATO and participation in the western alliance. To try and bridge this gap during the 2014 independence referendum, the Scottish Government in its white paper tried to appeal to both camps.

The result was a policy that could be said to have lacked clarity. In response, during the campaign the unionist side regularly attacked the SNP for being soft on defence.

The intervening years have been transformational. In the first case the UK’s own defence posture has become oddly distended with heavy investment in two very large weapons systems; Trident and the two new Queen Elizabeth aircraft carriers armed with extremely expensive F-35B aircraft. This had led to significant cuts in the nuts and bolts of national defense such as the army.

However even more important has been Brexit. The 2016 UK-wide vote to leave the European Union was strongly opposed in Scotland, where 62% of the electorate wanted to remain.

The reality of Scottish voters being forced out of the European Union against their will has led to a rapid and sustained growth in pro-Independence support. Many of these voters were originally opposed to independence in 2016 because they were worried that Scotland would not be allowed to remain in the EU and now have lessened their attachment to the UK as a whole. These voters are more centrist and multilateral, and their support for independence is probably conditional on an independent Scotland having as cooperative relationship as possible with other European states.

This growth of support by more centrist Scots in favour of independence has seemingly be matched by an important transformation in the SNP’s defence policies—most obviously in its recently released submission to the UK government’s integrated defence review.

This submission is measured, one might even call it mature. The overall thrust of which is to demonstrate that an independent Scotland would be an enthusiastic and useful member of NATO and would wish to cooperate closely with its Scandinavian partners in focussing on the High North.

To start with, one of the most striking things about the defence review is how little Trident is discussed. In an 11-page document Trident is only mentioned in two short, consecutive sentences, one of which criticizes the extremely high cost of the weapons system and another saying that money saved by not supporting Trident could be spent on other “conventional” weapons systems. This is hardly a pacifist position and is in line with the thinking of many now serving in the British Army.

If Trident is hardly mentioned, unilateral nuclear disarmament is not mentioned at all. Indeed in the discussion of nuclear disarmament it is specifically pointed out that any such achievement would occur through “multilateral” agreement (ie not forcing the UK to give up its own nuclear weapons except within a framework of an international move in this area). Considering how powerful the anti-nuclear movement had been in SNP politics to this time, such clear changes in emphasis are striking.

If unilateral nuclear disarmament is non-existent in the review, being a positive member of NATO and a serious military partner of Scotland’s northern neighbours is a constant theme. Indeed one of the most striking thing about the defense review is that the SNP is now arguing, quite cleverly at times, that an independent Scotland could actually be a more productive member of NATO than a UK which has over-invested in Trident and expensive aircraft carriers. For instance paragraph 31 of the report makes this fascinating claim. “Commitments to common NATO tasks, such as Standing Maritime Groups, must be prioritised over ‘out of area’ operations of dubious benefit, like FONOPS in the South China Sea. The United Kingdom cannot continue to ignore its own backyard while attempting to project hard power across the world – it must take a more active role in protecting regional security in the High North.”

In other words—Denmark, Norway, Holland, etc—and independent Scotland will work with you to focus on threats in our own area and won’t be gallivanting around the world playing at global Britain.

That ultimately is what makes this submission so potentially dangerous for unionists. The SNP is saying both to its European partners and the new supporters of independence who have been affected by Brexit that they can rely on an independent Scotland. The old criticisms levelled at the SNP that their defence policies are too extreme now will be much harder to make. Indeed, this review allows the SNP to argue with some force that their defence plans are realistic and directly attached to the interests of its neighbours and NATO partners. It is a serious document that will require a serious response.

Phillips O'Brien is Professor of Strategic Studies at the University of St Andrews