The UK has drawn up secret contingency plans to move its Trident nuclear submarine bases from Scotland to the US or France in the event of Scottish independence.
Another option under consideration is for the UK to seek a long-term lease for the Royal Navy’s nuclear bases at their current location in Faslane and Coulport on the west coast of Scotland. This would create a British territory within the borders of a newly separate Scotland, said people briefed on the plans.
The UK government is fiercely opposed to Scottish independence but the prospect of a potential break-up of the Union is worrying Whitehall. The governing Scottish National party returned to power in May and has pledged to ban all nuclear weapons in an independent Scotland.
Several senior officials told the Financial Times that the contingency plans for moving the submarines underscored the difficult choices ministers will have to make for Britain’s nuclear programme after a potential Scottish breakaway.
The exercise was undertaken recently, said people briefed on the plans, although one senior government official disputed the timing.
The exercise concluded that the Trident programme would have three options after the formation of an anti-nuclear independent Scottish state. The first would be to relocate the bases elsewhere on the British Isles, with the Royal Navy’s Devonport base cited as the most likely location to replace Faslane.
An analysis by the Royal United Services Institute think-tank written just ahead of the 2014 Scottish independence referendum estimated the relocation costs of such a move at £3bn to £4bn.
The second option would be to move the UK’s nuclear bases to an allied country such as the US, with one defence expert citing Kings Bay, Georgia, the base for the US Navy’s Atlantic fleet of Trident submarines. Officials also examined moving the UK’s submarine base to Île Longue in Brittany, France.
Moving the bases to the US is the preferred option of the UK Treasury, as it would require minimal capital investment, according to officials. But basing Trident outside Britain could be politically difficult, as it would likely be viewed as a threat to defence sovereignty.
The third option is to negotiate a new British Overseas Territory within an independent Scottish state that would contain the Faslane and Coulport bases, dubbed by one insider as a “Nuclear Gibraltar”.
Following negotiations on Scotland exiting the UK, Whitehall would hope to lease the land for “several decades”, according to officials.
The Ministry of Defence said there were “no plans” to move the nuclear deterrent away from Scotland, noting its contribution to the security and economy of Scotland and communities across the UK.
“The UK is strongly committed to maintaining its credible and independent nuclear deterrent at HM Naval Base Clyde, which exists to deter the most extreme threats to the UK and our Nato allies,” a spokeswoman said.
The MoD declined to comment on contingency plans for a Scottish breakaway.
Asked about the UK contingency plans, the Scottish government said it firmly opposed the possession, threat and use of nuclear weapons and was “committed to the safe and complete withdrawal of Trident from Scotland”.
Tom Plant, director of proliferation and nuclear policy at Rusi, described such contingency planning as “sensible”, but said that all options have “major drawbacks”. Moving the base to another country, such as the US, would also have operational repercussions.
“If we’re sharing infrastructure [with the US] then there are presumably intersections with US submarine patrol timings,” Plant said, explaining that the logistics of deploying the deterrent would have to be negotiated with the hosting nation. “Once the boats are at sea, they would still be as independent as they are now. But once they’re tied up alongside, they would no longer be independent.”
The “Nuclear Gibraltar” option — whereby the bases remain in an independent Scotland but are leased back by the UK — is preferred by some in Whitehall as the most realistic as it would not require immediate changes to the Trident programme following Scottish independence.
But any negotiation to retain the bases for an extended period after independence would be likely to face strong opposition from the SNP, which has for decades made nuclear disarmament one of its core policies.
Before the 2014 referendum, the SNP said an independent Scotland would prioritise the speediest possible safe removal of nuclear weapons. “This would be with a view to the removal of Trident within the first term of the Scottish parliament following independence,” it said.
Experts have suggested that this timetable could be softened as part of wider discussions between an independent Scotland and the UK over issues such as currency arrangements, responsibility for the national debt and management of the new border between England and Scotland.
However, a long-term or extraterritorial compromise on Trident would go against the fundamental principles of Scottish first minister Nicola Sturgeon, who joined the Campaign for Nuclear Disarmament as a teenager even before she joined the SNP.
“Like many other Scots, I’ve always been appalled that Britain’s nuclear arsenal has been kept in my backyard,” Sturgeon wrote in 2019.