Asked whether he had ruled out an extraterrestrial origin for three airborne objects shot down by U.S. warplanes in as many days, General Glen VanHerck said: "I'll let the intel community and the counterintelligence community figure that out. I haven't ruled out anything."

"At this point we continue to assess every threat or potential threat, unknown, that approaches North America with an attempt to identify it," said VanHerck, head of U.S. North