The alleged sighting was reported by an unnamed man to the National UFO Reporting Center (NUFORC) in the US.
The witness says he saw the “flying saucer” convoy being driven on a road in the Fort Leonard Wood area of Missouri on February 1 at 10.15pm local time.
It is about 240 miles from the Wright Patterson USAF base, which is where conspiracy theorists claim crashed UFOs, and even alien bodies, have been hidden away by the military.
In a report to NUFORC, the man said: “I was driving north 15 miles north of Fort Leonard Wood on I-44 north last night at exactly 10:15 pm and saw a line of police cars spaced out about a mile with no traffic coming southbound.
“I noticed more police cars with lights keeping traffic held back in the distance about another mile and a semi with flatbed was in the centre.
“As the semi (articulated truck) approached, I couldn’t believe that the semi was carrying what appeared to be a saucer shaped object.
“I passed within a hundred or so feet of the semi going in the opposite direction.
“The semi was moving at a moderate speed and the area was somewhat illuminated and my 16-foot Penske truck was elevated so I had a clear view.
“It was dull metallic grey, with thick short legs coming from the center bottom like fence posts, and a thick central body tapering to very thin edges.
”It encompassed the whole trailer and was hanging over the edges with no cockpit or windows or markings.”