Minor in comparison to the scale of a country. Especially if you consider that the yield you can expect from anyone who is not Russia or the US will level at most a district of a large western city.

In no way I want to imply that such an event would not be absolutely horrible and an act of evil. But considering the actual damage that nukes do is what finally cured me of being scared shitless of nuke-wielding terrorists. And yes, I used to be really scared of that.