After searching for two months, Australia's Department of Defense claims to have "lost" all but one of its files concerning UFO sightings, which were requested by a newspaper through the country's Freedom of Information laws. This leads us to two, equally plausible theories:
1) Headquarters Air Command is lying about the missing files to hide from the public documents that would confirm the existence of extraterrestrial intelligence.
or, 2) Aliens stole the files.
The remaining file, by the way, is "Report on UFOs/Strange Occurrences and Phenomena in Woomera," which concerns "a sketchy series of sightings from around the country and overseas, including people living in towns near Woomera, in South Australia state."