I lived in Tokyo in 2013 when Kim Jong Un was threatening to nuke Tokyo. And they actually took it very seriously.
Kim Jong Il (his father) had died in 2011 and the world knew he just talks sh*t. But in 2013, Kim Jong Un was an unknown and could potentially take action. Then of course, being that Japan was so close he had the weapon range to actually hit Japan with very little warning.
I remember there were Anti-missile sites around Tokyo, but particulary around the Imperial palace, like this:
And there were Ospreys buzzing around everywhere too which was pretty awesome to see:
(PS: If you are a Neon Genesis Evangelion fan,
you can see the aircraft in Eva were inspired by Ospreys.
Apparently the sea between the two countries had tons of Anti-missile ships in it too.
Spooky experience, I thought about what I would do if there was a strike. I would get to the subway if I was close enough.
If I was home (in an 8th story apartment) I probably wouldnt be able to get to the ground floor fast enough.
I lived in Ikebukuro, so if Tokyo was the target I would have almost definitely been in it.