I can confirm that a plane fitting the above description landed at Shannon Airport on 9 May 1999 at 20.48 GMT. The purpose of the landing was to provide support for the very welcome visit to Ireland by the First Lady of the United States, Mrs. Hilary Clinton.
As is standard practice for all requests for clearance involving military aircrafts, permission for the landing was given on the basis that the aircraft was unarmed and carried no arms, ammunition, explosives, photographic or intelligence gathering equipment.
The same plane departed Shannon on 12 May 1999 at 16:08 GMT and its destination was Capodichino, Italy.