I don't think that anyone seriously fears that the world can be blown to pieces all together. But what one can fear and rightly so are regional things like in the Middle East India Pakistan the Korean Peninsula borders in Africa etc.

I'm a bit jealous. Until two days ago someone told me I am the most famous Korean in the world.

There are nuclear weapons in China Iran Korea and Pakistan. It wouldn't take much to send a couple of warheads off on this planet somewhere that would cause a lot of environmental damage then if you have got someone who wants to retaliate you have real problems.