Solid, dark-gray, triangle-shaped craft that hovered and flew without any sound.As my friend and I were driving west on Hyw 52, entering Portland city limits on the west side of town, we saw a triangle shaped craft headed our way, moving west from the east, directly over the hwy. It seemed to hover and it made no sound at all! It finally began to move as we drove under it. The craft did not bank as a plane would when it turned to change directions. It remained level and simple turned and slowly drifted off to the north. It stopped when we quickly turned around and as we approached it again I flashed my head lights franticly and it seemed to know that we were attempting to follow it. As we got under the craft, that was approximately 100 feet above us, it took off at high speed and as it was leaving, F-18s flew over us at a high rate of speed in pursuit of the triangle-shaped craft. We watched until they all were out of sight. The craft had two white lights on the back side of the triangle craft and a bright red light at the front (nose) of the craft. It was a dark gray color and completely solid. I am retired Army and have been stationed at Ft. Campbell 101st Airborne/Air Assault Division and have seen all the high tech special ops aircraft in their arsenal and I have NEVER seen anything like this triangle-shaped craft EVER! It made no sound at all and was able to hover in place and change direction quickly without making any noise. It was able to fly at high speed and outrun the F-18s that were in pursuit of it.