Ministers are under pressure to reinstate Devonport as a nuclear submarine base amid moves to break-up the United Kingdom.
Labour decided in 2009 that Faslane on the Clyde would be Britain's sole naval base for submarines, including the Trident nuclear deterrent, by 2017.
Three Trafalgar-class nuclear-powered submarines are being shifted there from Devonport in Plymouth. Within five years, the Westcountry base will only refit and refuel N-subs after being stripped of its status as home to operational submarines.
But the Scottish National Party (SNP) has an avowedly anti-nuclear stance, and pledges to remove Trident from Scotland if independence is secured.
One defence analyst said the question over the future of Trident is the "elephant in the room" for David Cameron as he this week began the fight to save the union. Oliver Colvile, Conservative MP for Plymouth Sutton and Devonport, said the three submarines should be retained in Plymouth, the only viable alternative base to Faslane.
He added: "It would be short-sighted to move them up there in the knowledge they could be thrown out again under Scottish independence."
Mr Cameron this week agreed to an independence referendum within the next 18 months, although Scottish First Minister and SNP leader Alex Salmond has announced a preferred date of autumn 2014.
The increasing push for Scottish independence has also encouraged Cornish nationalists to call for powers to be devolved to the Duchy.
Westcountry business leaders also hope for a revision of the Barnett Formula, the funding mechanism that lavishes hundreds of millions of taxpayers pounds on Scotland.
Commentators say moving the entire nuclear submarine apparatus to Devonport, still a baseport for surface ships, would be extremely difficult. There is no English equivalent to the massive Coulport site that stores warheads and missiles, for instance.
Iain Ballantyne, editor of Westcountry-based Warships magazine, said: "If David Cameron is trying to get people to think what the implications will be of Scottish independence, the elephant in the room is what will Britain do with its nuclear deterrent.
"What Plymouth MPs could be suggesting is that the Ministry of Defence (MoD) should not be moving the Trafalgar-class submarines up to the Clyde, which would mean that the option of Plymouth remains."
An MoD spokesman said it was too early to comment. Alison Seabeck, Labour MP for Plymouth Moor View, said: "I will be writing to the minister to seek the Government's view on this. But I think any action would be premature."