I think that is part of it, but I think they also fear direct attack, or the threat of direct attack being used to undermine their geopolitical goals and autonomy.
People who view this as paranoid are simply not being rational. MAD is a defense against complete invasion, but not a defense against strangulation via power projection. They are encircled by the US which has invaded and toppled more regimes than any other country in the world, and destroyed or destabilized several Russian allied countries in the last 2 decades alone.
