Unidentified Aerial Phenomena (UAP)

Apparently the term "UFO" is out; in its place, "UAP," for "Unidentified Aerial Phenomena," is gaining popularity.

Jon Hilkevitch of the Chicago Tribune says:

The Unidentified Aerial Phenomena (the term that extraterrestrial-watchers nowadays prefer over Unidentified Flying Object) was first seen by a United ramp worker[....]

--"In the sky! A bird? A plane? A ... UFO?", by Jon Hilkevitch

But other sources suggest that the "UAP" term is actually an older term, and TSOR hasn't led me to anything definitive one way or t'other. Any thoughts?