22 May 1986 (Ocala Star-Banner, Florida)
The Brazilian Air Force dispatched four fighter jets, two F-5Es and two Mirages, to find several tiny UFOs which were sighted over Brazil on 19 May 1986, according to this article:
The Air Space Defence Centre had located the UFOs over the cities of Sao Paulo, Sao Jose dos Campos and Rio de Janeiro.
Quote from the article:
“One of the F-5 pilots reported seeing objects that he said were multicolored, (Brigadier General) Moreira Lima said, adding, ‘He reported that 13 of these objects accompanied his aircraft, seven on one side of his jet and six on the other side.’ ”
NOTE: On 29 September 2008, I posted a report on the small UFO sphere that I found in "The 10 Best Fighter Jets" (Discovery Channel) documentary film. The UFO flew near a U.S. Air Force F/A-22 Raptor (now designated F-22A) before ascending into the sky.
Military Channel (Discovery Communications) video
(the UFO footage can be seen at 1:25 minutes into the video):
Official roll-out of first USAF F-5E Tiger II (text by Wikipedia)
Royal Australian Air Force Mirage IIIO(F) (fighter) from
2 Operational Conversion Unit (text by Wikipedia)