This presents particular problems in terms of jobs, as there are thousands of Scots working in the defence industry.
SNP defence spokesman Angus Robertson says that other nations would still buy the best defence products from an independent Scotland, but Sweden lost lots of defence contracts when it insisted it wouldn’t be a member of Nato.
It’s hard to imagine England agreeing defence contracts with an independent Scotland to keep Scots in work while at the same time taking away jobs from places like Newcastle or Manchester. The SNP’s anti-Nato stance is a legitimate policy, but it’s one with consequences. There are also questions such as where an independent Scotland’s troops would be trained and where they would carry out military manoeuvres.
There’s also the issue of the European Union and the common defence policy set out in the Lisbon treaty. If an independent Scotland were to join the EU, this is something Scottish Government ministers would have to consider.
Although an independent Scotland wouldn’t be forced to be part of Nato, it would be very difficult not to be part of discussions about operations over the North Sea, for example, that involved radar surveillance.
These are also issues on which the jury is very much still out.
• Trevor Salmon is professor of politics at the University of Aberdeen.