Trident would a "strong bargaining card" for the government of an independent Scotland helping it secure a good settlement with the UK, according to a leading defence expert.

But Professor Malcolm Chalmers, the deputy director general of the Royal United Services Institute in London, also warned that simply expelling the nuclear submarine weapons systems, currently based at Faslane on the Clyde, would make negotiations on a new security deal between the new Scottish state and London 'difficult', and Nato membership "very difficult".

Professor Chalmers' comments come after the Scottish Government launched its latest papers making the case for independence. The document re-states the party’s long-held position of removing nuclear weapons “in the safest and quickest manner possible” following any Yes vote. It also confirmed the party's position, held since 2021, on an independent Scotland seeking to join Nato.

External Affairs Secretary Angus Robertson said that he wanted the weapons removed as quickly and safely as possible in an independent Scotland, but refused to put a timescale on the changes or a price tag on his plans to set up defence capabilities.

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The paper, titled An Independent Scotland’s Place In The World, highlighted the successful applications to Nato of Finland, which joined last year, and Sweden, which will accede this year, as examples of small, northern non-nuclear countries becoming part of the alliance.

Neither of these countries had weapons of mass destruction to remove when their applications were accepted putting an independent Scotland in a different position from them as it would face questions about when it would want to scrap them.

Professor Chalmers told The Herald that an independent Scotland would likely have to keep Trident for "at least" ten years until the UK could build an alternative base.

He said: "On Nato membership, other member states would likely follow the lead of the UK. Provided that London and Edinburgh reach agreement on the future of the Clyde nuclear bases, the door to Nato membership for Scotland should be open.

READ MORE: SNP insist ousting Trident 'not an obstacle' to Indy Scotland in NATO

"But it is likely to require at least a decade to develop a new base for Trident in England. Expelling Trident before there is a safe and secure place for it to move would trigger a strong reaction from London, making it more difficult to negotiate a strong bilateral security relationship and making Nato membership very difficult indeed."

He added: "On the other hand, Edinburgh’s acceptance of Trident basing would be a strong bargaining card, helping it to secure a good independence settlement and an entry ticket into Nato."

The paper also proposed setting up a single Scottish security and intelligence agency after independence, which would carry out spy operations “in line with Scotland’s values” and be overseen by ministers and the Scottish parliament.

READ MORE: Cost of new independence papers revealed by ministers

In December Jens Stoltenberg, the Nato secretary-general, warned that Russian President Vladimir Putin will wage war elsewhere if Russia defeats Ukraine. Concerns have also been raised that the Kremlin’s next targets could be Moldova and the Baltic countries.

Mr Robertson argued that removing Trident from the Clyde would not embolden Putin to strike out elsewhere.

He said: “So I think actually, having a northern European neighbour that understands the geostrategic situation of Scotland, and has the priority of our immediate northern European neighbour as a priority, which the United Kingdom does not, is one that I think anybody, including Vladimir Putin or anybody else who’s prepared to be involved in practices which are detrimental to our treaty allies, would take very seriously.”

He confirmed that Scotland would not have any submarines as part of its defence force, instead focusing on maritime patrol aircraft. The paper said that the armed forces of an independent Scotland “would comprise land, sea and air components overseen by a joint forces headquarters” at Faslane.

Mr Robertson committed to an independent Scotland spending 2% GDP on defence, in line with Nato guidelines, and would “participate fully” in the EU’s common security and defence policy.

He refused to say when asked how much it would cost to establish new armed forces and instead repeated the 2%  figure for continued spending once the services were set up. He also said that a defence and security review, which would take place after any Yes vote, would be key to estimating costs.

Other plans included in the paper outline establishing a dedicated diplomatic network, relying on sharing resources with EU states rather than just the UK and a commitment to meet the UN’s target of spending 0.7%  of gross national income on international aid.

A Scottish Government spokesperson said: “This Scottish Government’s position is clear; nuclear weapons should be removed from Scotland in the safest and most expeditious manner following independence.

“An independent Scotland’s position would be similar to the approach of most NATO member countries which neither possess nor host nuclear weapons. Finland's successful application to join the Alliance came after it publicly ruled out hosting nuclear weapons.”