The SNP is to vote on whether it should overturn its longstanding opposition to Nato.
Delegates at the SNP autumn conference in Perth will decide whether the party should back taking an independent Scotland into Nato on condition that it would be able to remove its nuclear weapons.
A motion has been tabled by SNP defence spokesman Angus Robertson, who warned on Thursday night that withdrawing Scotland from Nato would be like "pulling the plug on the radar" protecting the North Sea.
"Everything that is around Scotland turns into a black hole where we have no idea what's going on, and that worries our neighbours intensely," he said.
But he suggested he would take the risk if Nato insisted that Scotland must keep its nuclear weapons. "Politics and risk go hand in hand. Sometimes you just need to stand up and say this is something we need to advance and this is something we need to deal with," he said.
A former Nato secretary general has warned that an independent Scotland's membership of the organisation is "uncertain at best".
Lord Robertson of Port Ellen questioned whether membership of Nato would even be open to Scotland under the terms of the proposed SNP policy. Lord Robertson, who was Nato secretary general between 1999 and 2004, accused the SNP of wanting to "pick and mix with Nato's rules".
In a statement released through the Better Together campaign, the Labour peer said: "The SNP's camouflage of credibility on defence is fundamentally undermined by the contradictions in their own policy. They want to remain part of the Nato Alliance while ditching its most important strategic partnership."
But Angus Robertson said the comments were an "insult" to service personnel who had lost their jobs over the last decade.
Protesters are expected to demonstrate outside the conference. Leonna O'Neill, from Faslane peace camp, said: "Delegates are saying that they want to stick to the longstanding SNP policy on the grounds of principled opposition to nuclear weapons."
