Space.com: Mystery Aircraft/UFO Sightings on Rise

Sightings of a mysterious "black triangle" are on the rise, according to this latest article on Space.com. For my previous, related comments, see "And Iran". The current Space.com article presents theories advanced by the Las Vegas -based National Institute for Discovery Science:

A key NIDS conclusion is that the actions of these triangular craft do not conform to previous patterns of covert deployment of unacknowledged aircraft. Furthermore, “neither the agenda nor the origin of the Flying Triangles are currently known.”

The years 1990-2004 have seen an intense wave of Flying Triangle aircraft, the study observes. Sifting through reports by hundreds of eyewitnesses, the NIDS assessment states that the behavior of the vehicles “does not appear consistent with the covert deployment of an advanced DoD [U.S. Department of the Defense] aircraft.”

Rather, it is consistent with (a) the routine and open deployment of an unacknowledged advanced DoD aircraft or (b) the routine and open deployment of an aircraft owned and operated by non-DoD personnel, suggests the NIDS study.

“The implications of the latter possibility are disturbing, especially during the post 9/11 era when the United States airspace is extremely heavily guarded and monitored,” the NIDS study explains. “In support of option (a), there is much greater need for surveillance in the United States in the post 9/11 era and it is certainly conceivable that deployment of low altitude surveillance platforms is routine and open.”

Note the fine distinction: not "covert", but rather "unacknowledged"; that is (so the theory goes), the Defense spooks aren't trying too hard to keep this thing a secret - they want our adversaries to know just enough to worry them.