My guess is that this has something to do with the Navy’s “super-secret” AURORA project:

They have become legendary in UFO circles. Huge, silent-running “Flying Triangles” have been seen by ground observers creeping through the sky low and slow near cities and quietly cruising over highways.

The National Institute for Discovery Science (NIDS), has catalogued the Triangle sightings, sifting through and combining databases to take a hard look at the mystery craft. Based in Las Vegas, Nevada, NIDS is a privately funded science institute with a strong research focusing on aerial phenomena.The results of their study have just been released and lead to some unnerving, still puzzling conclusions.

The study points out: “The United States is currently experiencing a wave of Flying Triangle sightings that may have intensified in the 1990s, especially towards the latter part of the 1990s. The wave continues. The Flying Triangles are being openly deployed over and near population centers, including in the vicinity of major Interstate Highways.”

But, due to the end of the Cold War, the need for secrecy has become not nearly so marked as with the B-2 or F-117 projects.

hat tip: reader Kayse