Newly declassified files from Britain's Ministry of Defence shed further light on why the military shut down its UFO desk nearly three years ago, despite a surge in reported sightings - the expensive operation just had no defence benefit.
The National Archives has been releasing declassified Ministry of Defence files on UFOs for the past five years.
The 10th and final tranche released yesterday covers the work carried out during the final two years of the Ministry of Defence's UFO desk, from late 2007 to November 2009.
The 25 files detail reports of alien abductions, UFO sightings, offers to develop weapons to shoot UFOs out of the sky - and the reason for the UFO desk's shutdown.
Among the documents - over 4,400 pages - was a memo to then-defence minister Bob Ainsworth in November 2009, saying that the UFO operation was "consuming increasing resource, but produces no valuable defence output".
In more than 50 years, no UFO sighting report "has ever revealed anything to suggest an extraterrestrial presence or military threat to the UK", the previously classified memo said.
The records show that 2009 saw 600 UFO sightings and reports - triple the number of the previous year and the largest since 1978, the year Close Encounters of the Third Kind was released in cinemas.
Whatever the reason behind the surge - some files suggest the popularity of releasing Chinese lanterns at weddings was behind it - the decision was taken to close the desk.
"The level of resources diverted to this task is increasing in response to a recent upsurge in reported sightings, diverting staff from more valuable defence-related activities," the documents said, with one saying the desk "merely encourages the generation of correspondence".
Among the sightings were reports of UFOs seen hovering opposite the Houses of Parliament and near Stonehenge.