I work these issues on a daily basis, so perhaps I can help answer some of your questions.

I've been wondering of late, since the US military depends at least in some measure on satellites, is near-earth space in danger of becoming too highly populated by non-American traffic for our military to dependably use?

Well, the term "near Earth" has a specific meaning in the space community. A "near Earth orbit" is one with a period of less than 225 minutes. The US military actually doesn't have very many satellites in that region, primarily some weather satellites and some others that I can't talk about. Most military satellites are higher in deep space, such as the GPS constellation in 12 hour orbits or a host of satellites out at geosynch for things like communications and launch detection.

I mean with China, India, and whoever else at least talking about moving into near-earth space in a serious way, does that change where we want to put our military space assets?

Like I said, we don't have much in near Earth orbits but there are things there that are civilian satellites that are also used by the military to a degree, such as the Iridium constellation. The other missions are in less accessable orbits. There really isn't much need to move to greener pastures and there's no good substitute for the geosynch orbit, so I don't see much changing.

Or how about (a long shot, no pun intended) a command and control center on the moon? Talk about your rear lines...

Well, I've always heard that the higher your rank, the further you are from the combat zone. In that regard, the moon would be a good place for a 10 star general, I suppose. Really, the moon wouldn't be very good for C2 because of the expense and the propagation delay.

You can rest assured that the US military is taking measures to protect our space assets, but this is another topic that I can't talk about very much. You can go find some unclassified material on space control in Joint Publication 3-14 and Air Force Doctrine Document 2-2. The joint community refers to Protection, Prevention, and Negation but the Air Force talks about Defensive Counterspace and Offensive Counterspace.