Admittedly, the scenarios I have outlined are implausible, but they serve to illustrate a point. If we are absolutely terrified to use our nuclear weapons, we make the probability of nuclear war higher, not lower. 

[quote=Chapatrap]
Why would they nuke London? Relations have been chilly since the Second World War and not once have they bombed Britain. Just because we're having our generational spat with Moscow doesn't mean we're going to get turned into a Fallout gaem.
[/quote]

You're right, they wouldn't.

[quote]whether that's exchanging capital cities, or nuking armies to 'dissuade them from using the nuclear threat so casually in the future.'[/quote]

Did I say armies? Because I thought I said silos. Feel free to correct me

Having outlined the unrealistic scenarios, time for a realistic one.

http://www.foreignpolicy.com/articles/2014/09/04/putins_nuclear_option_russia_weapons