The US doesn't use such weapons because we don't want them used on us. We have the advantage in a conventional war, and we want to keep it that way. We don't want to start a space weapons race.
Oh really!?!?

I have read numerous sources quoted from U.S government personell that seemed very interested in exploiting space for their own purposes.

In fact, I believe the USA is one of the few countries who have not (suprise, suprise) signed an international agreement stipulating that space is not for national exploitation and is for "everybody"

And to believe a nation would 'prefer' to send men off to die rather than obliterate cities from the comfort of the Pentagon games room strikes me as a bit far-fetched. Why bother with Nuclear weapons or germ/gas etc etc