[Ari]

Well I've heard it can sometimes take out a pre-set target that uses minimal counter measure systems. That is when the interceptor missle doesn't explode seconds after launch.

Kimmy might be a bit crazy but he does seem to want to keep his country around. An ICBM attack on the US (possibly even with a plain warhead) would probably result in a new glass parking lot for south korea. So an ICBM attack from a country that doesn't appear to have a single working rocket is low on the list of possible dangers to the US.