Three bright white lights in synchronized flight.

Three separate bright white lights spotted on a relatively clear and quiet night.  One following behind the other, traveling due east.
 Why it was unusual and caught our attention is that they were extremely high in the sky, at first mistaken for stars.  The lights were the size of a large star seen in the sky this night.  The lights were steady, not flashing.  They were traveling quite fast as compared to the very visible planes passing nearby, and they flew in a synchronized line.  They made no sound.