The Faslane base on the Clyde is undergoing expansion as part of a plan to relocate all Royal Navy submarines to the base by 2017. Faslane is already Scotland's largest employer, and cost estimates for replicating its capabilities elsewhere vary from considerable to astronomical. Similarly, the Coulport site, where missiles are stored, would need to be replicated outside an independent Scotland. Alternative sites, such as Barrow or Plymouth, would require extensive and expensive modification, which would take at least a decade to implement.

Salmond—who suggests that British Trident equipment could be moved to France or the U.S.—has noted that if Scotland refuses to host Trident, the U.K. may well end up having to decommission its nuclear deterrent.

The defense posture of an independent Scotland creates a host of issues to juggle, but the suggestion that an Edinburgh government could effectively force the U.K. into nuclear disarmament is potentially the most divisive. In evidence to (the London) Parliament's Defense Committee, Prof. Malcolm Chalmers, research director at the Royal United Services Institute, was blunt in his assessment of the political maneuvering that could take place.

“If a Scottish government said, 'Right, we want to be non-nuclear, and we want to do it now, these submarines have to be back in England by next Tuesday',” he argued, “the U.K. government would say: 'OK, you want our support to become members of the European Union; you want the Bank of England to support your currency, or to share a currency with the U.K.; you want to have free trade and you want your Scottish personnel to be able to serve with the U.K. Armed Forces: well, get real. We have needs as well'.”

Given such serious outstanding issues, expanding cross-channel defense collaboration, while promising, is not going to happen without assertive leadership.