It could also be a test of the missile shield. Like this one http://www.spacedaily.com/reports/Japan_says_succeeds_in_mis...
Even the patriot missiles back in the early 90's always awed me. I have trouble hitting a target in a consistent spot with a bullet from 100 yards.
http://en.wikipedia.org/wiki/MIM-104_Patriot#Success_rate_vs...
Think about the margins of error involved - how precisely do you have to know the Patriot rocket's position, vector and speed to intercept something falling from space? How do you take into account the fragmentation issues of a device like a MIRV? How do you account for any differences in the target projectile's path?
It's just an astounding problem to me. I very much dig the thought that I'm the same species as those that figured it out.
First and foremost, it is being able to convince your opponent that you can do that.