GA, you should read The Moon is a Harsh Mistress, and read it in conjunction with this Wikipedia article: http://en.wikipedia.org/wiki/Kinetic_bombardment. It provides a very good explanation of just how important holding that particular high ground is.
Read it ages ago - when it was first published. Great FICTION, but it is FICTION; it is NOT reality. That NOVEL presupposes an industrial capacity on the moon that approaches the USA today. There is no self sustaining industrial capacity on the moon. There is no industrial capacity on the moon at all. The cost of producing such is beyond the capacity of even the largest national economies. They don't call economics the "dismal science" for nothing. It kills grandiose pipe dreams like this onw with the harsh realitles of cost. You should read a few FACTS like that actual cost of delivering a kg of material to the moon, and the actual cost of returning an oz of material from the moon ($1,783,000) in 1970 dollars.