15 of the remaining 18 UFO files awaiting publication by the United Kingdom's Ministry of Defence (MoD) following their large 2013 release have been made available to the public. Unlike the 2013 release, these files are not available online, and must be viewed onsite at the MoD's archives in Kew, a suburban district in the London Borough of Richmond upon Thames.

According to a press officer with the National Archives, "15 files from the MoD on the subject of UFOs have been released. We release files on a weekly basis and have already highlighted previous releases on this subject. With this release comprising of a small number of files, it has not been practical to prepare a full press pack. However, the files are available for all members of the press and public to view in our on site reading room here at Kew."

The files contain records of some of the UK's most famous UFO sightings, including the event at Rendlesham Air Base in 1980, known as 'Britain's Roswell.'

Nick Pope, who ran the MoD's UFO project from 1991 to 1994 says that there is no 'smoking gun,' in the files, and speculates that this might cause UFO conspiracy theorists to believe that the government is holding something back.

"'I think these files perfectly capture the wonder and fascination of the UFO mystery and show how MoD officials - myself included - struggled to make sense of one of the great mysteries of the modern era," said Pope.

"Sadly, there's no 'smoking gun' in these files that will prove we've been visited by extraterrestrials, but there are plenty of intriguing UFO reports, as well as policy papers explaining how the MoD handled this subject."

"The lack of a smoking gun and the fact that these files seem to have been slipped out without a formal media announcement is bound to start some conspiracy theories, and I know that many people believe the 'good stuff' is being held back."

However, the obfuscation of the MoD's interest in UFOs should be of interest to the public, said the former MoD employee.

"What's readily apparent from a detailed study of all this is that the MoD was telling Parliament, the media and the public that the UFO phenomenon was of 'no defence significance' and of limited interest to the MoD," said Pope.

"However, the files show that behind the scenes, the subject was obviously taken more seriously than we let on, with many of the cases self-evidently being of great defence significance – e.g. when UFOs were seen in close proximity to military bases, were encountered by RAF pilots, or were tracked on radar by fighter controllers or air traffic controllers."

The remaining three files are due for release later this year, and Pope maintains that this most current release itself is a positive step.

"This is a good day for open government and for freedom of information."