black triangular craft seen by truck driver, prior military and law enforcement.I drive 18 wheelers and was traveling us 80 just outside of Dallas. I saw what I thought was a fighter jet run in front of my truck but had no lights or sound and was traveling from the north east heading to the south west and an extremely fast speed. I lost sight if it and tried finding it in my passenger side mirror, I regained sight of it in my driver side mirror and saw the craft heading back towards my truck in which looked like it was following the highway at the speed it was going prior to this maneuver it would of been impossible and at this time I knew it was not a fighter jet. It quickly gained on my truck and was now directly to the left of me in an open field. I was traveling at approx 65 mph and the craft was to the left just ahead of me. I now noticed it had three lights and was triangular in shape and appeared to be black in color. It was approx 200-300 feet off the ground and unknown length since there was nothing to judge the size against. It followed for approx 15 to 20 seconds, and then while I'm still following beside it, it shot directly up and was gone from view. I got the strong feeling while I was watching it and after it was gone that I was not supposed to see it. There was another truck ahead of me, and I they had to see it as well