I remember reading about this a few years ago – the use of telephone pole size tungsten rods dropped from space onto far away targets requiring immediate destruction. Advocates have also described the use of crowbar size rods. I like the idea and hopefully we are looking into it. This Wikipedia link describes it in more detail http://en.wikipedia.org/wiki/Kinetic_bombardment

Of course the militarization of space is a concern, but I believe it is inevitable. How much something like this would cost is unknown, but I’m sure it would be big bucks. The upside – the ability to strike anytime and anywhere. The downside – collateral damage, weapons race.