Government UFO-related documents seem to have a habit of disappearing. This time the files belonged to the Defense Intelligence Agency (DIA).

John Greenewald has been using the Freedom of Information Act (FOIA) to get formerly classified documents from the government, and to post them online for decades. He began his efforts while in high school in the 1990s and continues his efforts to this day.

Greenewald was inspired to seek out these documents when he heard of UFO files that showed the U.S. government's interest in a UFO incident in Iran that took place in 1976. The government claims it no longer had any interest in UFOs since the official closing of its official UFO investigation, Project Blue Book, in 1969. He requested the document through a FOIA request and, to his surprise and delight, received it.

The file -- and the process of retrieving it -- fascinated Greenewald to the point where it spawned what has become a lifelong effort to retrieve formerly classified files and post them on the Internet. Greenewald's website, TheBlackVault.com, now has over 1.3 million formerly classified pages of documents.

In 1996, in response to a FOIA request, Greenewald received nearly 250 files from the DIA regarding UFOs. Supposedly, everything they had on the topic. However, several of the files were heavily redacted, meaning that there were blacked out sections, presumably, because those portions contained information that is still considered classified.

Occasionally, Greenewald requests that these files undergo a Mandatory Declassification Review (MDR). The government is then supposed to review the previously declassified document to determine if redacted material can be unredacted, due to the information that had previously been blacked out having since been declassified.

It was an MDR of a classified document about spy planes that allowed the term Area 51 to be unredacted, thus making the existence of the super secret Area 51 military base official. Of course, that location had already been famous in UFO circles and popculture.

In 2014, Greenewald requested an MDR for the DIA documents he had obtained in 1996. In his inquiry, Greenewald included links to download the files he had received from the DIA which he now wanted reviewed.

Months later, in mid-2015, Greenewald received a reply that the links he had provided did not work, so the case would be suspended. The responses by the DIA are actually a bit confusing, but it appears once Greenewald's links could be accessed, the files he requested were not found.

The DIA wrote, "It appears the FOIA case files have been purged from the FOIA database."

Why, of course they were. To read more, click here.