The party’s policy-making national council will decide whether to abandon its opposition to membership of the western defence pact in June.
The move has already sparked a rift within the SNP ranks, with a senior MSP warning that backing for Nato’s commitment to a nuclear alliance would be at odds with the party’s anti-nuclear stance and opposition to the Trident submarine fleet at Faslane.
The move comes after a series of policy retreats by the SNP, including the claim by finance secretary John Swinney that an independent Scotland would continue to use the pound for at least a decade following a split with the UK.
Nationalists also now want to have the devo-plus option, which would see Holyrood take control of most taxes, included on the referendum ballot as an alternative to full independence – another policy shift by the SNP.
Senior party sources were reported yesterday to have revealed the policy shift, with the national council due to vote on the issue in Perth on 16 June. Party sources later confirmed the position to The Scotsman.
However, senior MSP John Wilson, the deputy head of Holyrood’s economy committee, said he would oppose the reversal of the party’s opposition to Nato, which he claimed would be “incompatible” with its anti-nuclear stance.
Mr Wilson warned that ditching the policy, which the party has held for 30 years, would weaken the international standing of an independent Scotland.
“There are no meaningful benefits to the people of Scotland from this,” he said. “An independent Scotland would meet its peace-keeping obligations through its membership of the United Nations.
“The current policy of the SNP is to oppose not only the siting of nuclear weapons in Scotland, but also the Nato commitment to the use of nuclear weapons as a first strike option.
Membership of Nato would be incompatible with the current party policy on nuclear weapons.”
Another MSP Jamie Hepburn had previously lodged a Holyrood motion to mark the 60th anniversary of Nato, saying that the alliance was a destabilising factor in the West’s relationship with Russia, that it relied on the continued use of nuclear weapons, and that it served no useful purpose in the modern world.
However, Nationalist Euro MP Alyn Smith, a member of the national council, yesterday hinted that he would back a change in the anti-Nato stance and said most SNP members did not see opposition to the defence pact as a “priority” in the run-up to the 2014 referendum.
Mr Smith said: “It’s up to the members of the party, but all things need to be on the table. I sit in the European Parliament, and there are a lot of sensible countries that are in Nato, which I’m sure the SNP will be pragmatic enough to look at.
“There are an awful lot of Danes and Norwegians who look at Nato as being a sensible thing to be part of.
“This is an evolution of Scottish politics, and it’s not a softening of the position at all.
“My view is that most members are not greatly fussed about the issue of Nato membership and opposition to it. They don’t see it as a priority.”
Angus Robertson, the SNP’s defence spokesman, has also previously hinted at an independent Scotland being part of Nato, and has written about other nations with an anti-nuclear stance, such as Norway and Denmark, being part of the alliance.
He wrote: “Despite different relations to treaty organisations, such as the European Union and Nato, the Nordic and Baltic nations are pushing ahead together as never before.
“This includes shared basing, training and procurement arrangements. For nations like Norway and Denmark, in particular, deployability and reach within the High North and Arctic is a key consideration.”
Former SNP leader Gordon Wilson, who failed to get the SNP to abandon its opposition to Nato in the 1980s, said a policy change would boost support for independence.
He said: “There’s nothing harmful in being a member of Nato, and from a strategic point of view it will help in the arguments against those opposing independence.
“By seeming to be in the swim, it will possibly reassure people that we’d be safe and secure in an independent Scotland.”
A comprehensive survey of the SNP’s membership by James Mitchell, professor of politics at Strathclyde University, earlier this year revealed that more than half of grassroots members disagreed with the SNP’s plan to withdraw from Nato.
Last night, Prof Mitchell said his research suggested any proposal to remain part of Nato would get a fair hearing from the representatives of the SNP membership at the meeting of the national council, which meets twice a year.
He said: “The majority of members would support Scottish membership of Nato, but it has to be said that it is a bare majority and the strength of feeling on this is not great.
“In other words, very few of the SNP’s members feel that this is a matter of great urgency and great importance.”
One of Britain’s leading defence experts, Professor Malcolm Chalmers, has claimed that signing up to Nato would mean the Trident submarine fleet and its nuclear warheads being kept in Scotland possibly for decades.
Prof Chalmers, the defence policy director of the Royal United Services Institute, said the SNP’s anti-nuclear stance would be “hard to square” with an independent Scotland accepting Nato’s commitment to a nuclear alliance.
Opposition parties yesterday attacked the SNP’s review of its Nato stance as a “cynical attempt to win votes” and reassure voters ahead of the independence referendum.
Scottish Conservative leader Ruth Davidson said: “First, the SNP changed their mind about keeping the Queen, then they changed their mind on the pound, now they are changing their mind on Nato.
“Alex Salmond simply does not get defence – a view shared by numerous military experts.
“After all, this is the man who derided Nato’s humanitarian mission in Europe to prevent acts of ethnic cleansing as one of ‘unpardonable folly’.
“Alex Salmond has no love for the armed forces, and this is nothing more than a cynical attempt to win votes.”
Labour’s shadow defence secretary, Jim Murphy, said: “The SNP just don’t get defence. They want to take Scotland out of the British Army, Royal Navy and RAF and end Royal Navy shipbuilding on the Clyde.
“As defence experts said only last week, none of our allies would understand what message Scotland was trying to send by opting out of an alliance that has been the central player in security for the last six decades. Being in Nato is important not just for our defences, but for Scotland’s manufacturing industries and all the high-skilled jobs they support.
“In a globalised world, Scotland needs to have alliances. Being in the UK and part of Nato are two important partnerships, and separating from either would be strategically unwise.”
An official SNP spokesman dismissed as “mere speculation” reports that its leadership was considering proposing a change to the party’s policy on Nato.
The spokesman said: “Our long-standing policy is to be a member of Partnership for Peace, like Sweden, Austria, Finland and Ireland, which provides for bilateral co-operation between Nato and non-Nato countries.
“Anything that may happen in the future is mere speculation. If a motion is submitted it will be considered by the party’s standing orders and agenda committee, who will decide if it goes forward for debate. This reflects the democratic processes at the heart of the SNP.”