but you have to remember that Russia and the USA is held by the Geneva conventions which prohibit any sort of nuclear, biological, or chemical weapon of mass destruction from being used. If you do happen to use one you could have the whole word against you in a single week (if not less), all aiming their nukes at you. Basically with this, the original target will be demolished from the prohibited weapons that were used against them (assuming they were used effectively which the USA nor Russia have any problem doing) and the original attacker will be demolished by a hail of nukes, ultimately destroying all life in the area. the only winners are those that abide by the Geneva Conventions which is why I think there hasn't been a nuclear fall out yet.