Withdrawing Scotland from Nato would be like "pulling the plug on the radar" protecting the North Sea, the SNP's defence spokesman has warned.
Angus Robertson hosted a seminar on the eve of a divisive vote at the SNP conference on overturning the party's long-standing opposition to the nuclear-armed military alliance.
Delegates will decide on Friday whether the SNP should back taking an independent Scotland into Nato on condition that it would be able to remove its nuclear weapons.
Mr Robertson laid out the stark reality of losing Nato air cover over Scotland, but said he would be willing to risk it if it came with the condition that Scotland would have to keep nuclear weapons.
He said: "Anything that flies towards Scotland is tracked by Norwegian and Danish air force officers who, if they believe there is a threat, will pick up the phone, ring Northwood and a jet is scrambled currently from Leuchars and in future from Lossiemouth.
"At the present time, air policing is done between all of our North Sea northern neighbours through Nato."
Mr Robertson said he was asked if the Scottish Government understood the importance of Nato air cover to the North Sea on a fact-finding trip with First Minister Alex Salmond to neighbouring countries.
"I asked what the impact would be of Scotland not being in Nato," said Mr Robertson. The answer came that the simplest way to describe it is pulling the plug on the radar. 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."
Briefing papers from the Ministry of Defence and the Foreign Office on Wednesday emphasised that Nato membership is not automatic for every state, and stressed that the SNP's anti-nuclear stance could impact on their membership bid.
Mr Robertson admitted he was taking a "political risk" in attaching an anti-nuclear condition on Scotland's Nato membership. "Politics and risk go hand in hand," he said. "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."