SNP policies include unilateral nuclear disarmament.
Putin wants his population to increase their birth rate. The last person to attempt this was called Hitler.
The threat of nuclear counterstrike is what keeps tank divisions off Europe's lawn.
"Do the math".
Footnote: As Nicola says, nukes are no use against terrorism. She is right about that but, inexplicably, forgets to make allowances for a major superpower, not that far away from us.
This is a "red line" for her so all their other "great" policies pale into insignificance, in my humble opinion.