In Civ 5 the nuclear missile unit can be used to destroy a city. Only a city that is not an original capital city can be destroyed. City-states cannot be destroyed even if they have been annexed, which makes them useful to take over if you're facing a nuclear-armed opponent. One missile cruiser can destroy an entire civilization in one turn. This is why cities have to be spaced out with more than three tiles between them. You lose the ability to bombard enemies from multiple cities, but it is harder for nuclear opponents to wipe out your cities.
Duration: 1m 44s