Scottish independence: Former Nato commander attacks SNP defence policy
The defence policies in the Scottish government's White Paper are "amateurish" and "dangerous", a former Nato commander has said.
General Sir Richard Shirreff, the former deputy supreme allied commander in Europe, also said Scotland's future Nato membership was uncertain.
Scottish Conservative leader Ruth Davidson said the SNP had "failed the test" on defence.
But the SNP said the UK had a "dangerous" nuclear defence policy.
In a letter sent to Sunday newspapers, Sir Richard said: "As an experienced professional soldier, nothing I have seen or heard persuades me that Scotland's safety or security would be enhanced one iota if it became a separate country.
"On the contrary, having reviewed the Scottish government's White Paper, I find the proposals amateurish, unrealistic and lacking any clear strategic purpose.
"There is no mention of any naval aviation (yet Scotland would need a primarily naval force), no mention of air-to-air refuelling capability, no mountain rescue and no search and rescue capability.
"The White Paper proposals are dangerous and would leave Scotland, the UK and Nato weakened and less capable of dealing with the threats of today and tomorrow."
The Scottish government's White Paper on independence proposed a defence budget of £2.5bn in an independent Scotland, with "air and sea-based patrol" and a total of 15,000 regular and 5,000 reserve personnel within 10 years.
The SNP, currently in power in Edinburgh, wants to remove nuclear weapons from Scotland within four years of independence.
The party ended its 30-year opposition to Nato in 2012, and has argued Scotland can transition to independent membership of the alliance.
Sir Richard wrote: "Nato is a nuclear-armed alliance and all Nato states must accept the principle of nuclear deterrence and being part of the Nato nuclear command and control system.
"Whilst the SNP may accept the principle of nuclear deterrence, it remains unclear how other members of Nato will view the disruption to the coherence of Nato defence caused by moving the submarine fleet out of Scottish waters."
Commenting on behalf of the pro-Union Better Together campaign, Ms Davidson said: "The first duty of government is the defence of the nation. On this evidence, the SNP has failed the test.
"General Shirreff makes it clear there is no certainty around an independent Scotland's membership of Nato.
"Worse, he concludes that the SNP's plans for a Scottish defence force are 'amateurish' and 'unrealistic'.
"For our servicemen and women to be faced with this prospect is an insult to their professionalism."
SNP defence spokesman Angus Robertson said: "A dangerous and amateurish defence policy would be one that sent troops into an illegal war without proper equipment, while wasting tens of billions of pounds on Trident nuclear weapons that can never be used.
"That's the UK."