Chinese DF-31 test launch is my guess
The http://i.afterdawn.com/storage/pictures/china_ufo2.jpg being pitched by some as a UFO, that forced closure of a Chinese airport, looks like the second or third stage of a solid fuel rocket.
Looks an awful lot like [this|this] 22 September 2005 Minotaur launch. (I actually viewed this from Arizona)
Minotaur's are just Minuteman II ICBMs, recycled with an orbital payload instead of a warhead.
So, that's my guess. In fact, I'd have to go with a spaceship from Mars, before I'd believe the US launched an ICBM over Chinese territory. :)