Is this a huge version of Darth Vader's lightsaber, as someone said in the comments? It actually does look like one.
Looking at the scale—compared to the tiny humans on the ground—and the strange external machinery attached to it, I thought this was part of some kind of huge experimental rocket. I was wrong, but kind of close.
It's the second interceptor silo for the Ground-based Midcourse Defense system. It's being installed now by Boeing and the U.S. Missile Defense Agency at the Vandenberg Air Force Base, in Santa Barbara County, California. You know, the missile defense system that is not going to save us from any nuclear mayhem, but maybe from some retards launching the occasional warhead. [Boeing]