I'd be less worried about Russia using a nuke directly as a state, and more about it doing what everyone feared in the fallout of the USSR collapsing.
They've already demonstrated a willingness for its materials to be used obviously on foreign soil with the barest pretense of deniability. I can't imagine they'd sweat too much if somebody set off a dirty bomb, and the willingness to take direct action in response isn't guaranteed by NATO.
I suppose it's somewhat up to how willing China and Iran are to ignore such an obvious act. The thing that actually keeps me up isn't their real response, but Russia's assumption of what it will be. Russia's predictive powers seem to err towards 'what we want is the right idea' more than 'we can actually get away with this', and they've simply taken advantage of tolerance more than weakness/fear.
They've already demonstrated a willingness for its materials to be used obviously on foreign soil with the barest pretense of deniability. I can't imagine they'd sweat too much if somebody set off a dirty bomb, and the willingness to take direct action in response isn't guaranteed by NATO.
I suppose it's somewhat up to how willing China and Iran are to ignore such an obvious act. The thing that actually keeps me up isn't their real response, but Russia's assumption of what it will be. Russia's predictive powers seem to err towards 'what we want is the right idea' more than 'we can actually get away with this', and they've simply taken advantage of tolerance more than weakness/fear.