As i understand it, HollyDaze, Trident is the UK's democratically endorsed independent (so-called) submarine-delivered nuclear deterrent, presently located at Faslane (the submarines) and Coulport (the missiles) in Scotland. The system is essentially American sourced, but maintenance and upgrading takes place at Aldermaston in Berkshire, so there is regular, and so far safe, movement of the missiles about the UK anyway.
Now we know that the SNP have given notice to the UK that they would demand that Trident be removed from Scotland, lock, stock and parcel within a tight timetable. That would, of course, be their right in which case the UK would have to relocate Trident south of the border or scrap it, which appears to be unlikely. Now I do not see moving Trident south (and all its jobs) as an insoluble problem, but in any case, a nuclear deterrent need not be delivered (heaven forbid!) by submarine anyway, but by much smaller and cheaper delivery systems. None of that would be any business of the SNP. I am not an expert in this so please excuse any errors or omissions.