The view is set out in a 62-page document, widely trailed over the weekend, which looks at a range of security issues facing the country in the event of a Yes vote in the referendum next year.
The SNP’s position that Scotland shares more burdens but fewer benefits of UK defence is “fundamentally flawed”, the report finds.
It questions whether developing new infrastructure and hardware would make the country any safer, suggests the defence industry could be dismantled and warns that the upheaval of rejoining Nato would add nothing to Scottish security.
Scottish independence will lead to difficulties in recruitment and retention, raising the prospect of “foreigners” filling the ranks, it claims.
And setting up new intelligence and “cybersecurity” structures may cause uncertainty in exchange for “no extra security”.
The full report, officially launched today by the Scotland Institute think-tank, suggests the SNP has “yet to acknowledge” the significance of its overall aim of political independence for Scotland.
The SNP insists leaving Westminster rule will stop Whitehall making “bad decisions on our behalf”.
‘Full significance of independence’
But referring to concerns for the banking sector and currency sharing plans after independence, the report states: “It is more and more evident that independence from the UK would be of great practical disadvantage to Scotland and those living within its borders.
“Fulfilment of political ambition may be some consolation in these circumstances, but this is not how the SNP is selling its case.
“The arguments put forward by the SNP leadership claim that independence will be beneficial to Scots in a practical as well as a political sense.
“That claim when applied to matters of defence and security, however, has been seen to be wanting.”
The authors of the report, overseen by Major-General Andrew Douglas Mackay, who commanded British forces in Afghanistan, concluded that the SNP has yet to acknowledge the “full significance of its demand” for independence.
SNP defence spokesman Angus Robertson, responding to the trailed report yesterday, said: “Rather than defend this appalling UK Government record in Scotland, we should welcome the prospect of better defence decisions in Scotland, securing jobs, conventional capabilities and facilities.
“To have serious credibility, this report must also outline Scotland’s vast defence assets, as an independent Scotland would of course not be starting from scratch. But the key difference is that after independence, Scotland would decide how to spend all of the money it contributes to defence.”
The SNP proposes a £2.5 billion budget for defence, which the party says is about £500 million more than currently spent by the UK Government in Scotland.
The Scottish Government says the country will have “first-class” conventional forces playing a full role in defence and international co-operation, without “wasting” money on the Trident nuclear deterrent.