From a Wall Street Journal story by Ben Zimmer headlined “‘UFO’: A Military Term Abducted by Fans of Aliens”:

The U.S. military recently dispatched fighter jets over North American airspace to shoot down three…well, what exactly?

The Pentagon has called them “high-altitude airborne objects.” At a press briefing on Monday, National Security Council spokesman John Kirby classified them as “unidentified aerial phenomena.” But as Rep. Jim Himes, ranking member of the House Intelligence Committee, acknowledged on NBC’s “Meet the Press,” most people just call them “UFOs,” regardless of the official terminology.