The US Air Force's nearly 130,000 pages of UFO records have hit the Internet.

There are countless bizarre sightings, hundreds with no explanation, and they are now easy to find online thanks to UFO enthusiast John Greenewald, who posted the entire collection for the first time last week on his site The Black Vault.

"There's absolutely something out there," he told ABC News. "The big question mark is: 'Have they come here?'"

UFO enthusiast John Greenewald posted the entire collection of 130,000 Air Force UFO documents for the first time last week on his site The Black Vault. ABC News photo.

Greenewald spent 20 years requesting and then collecting, collating and studying the documents. Though the papers had been declassified years ago, they were not easily accessible by the public.

FBI vault reveals UFO and Roswell files.

Something strange in the skies.

UFO sightings caught on tape.

After the infamous alleged alien landing in Roswell, New Mexico, in July 1947, the US Air Force investigated 12,618 sightings from 1947 to 1969.

The cases were known as Project Blue Book and made up the bulk of Greenewald's document dump.

"The military and the government want you to believe there's nothing to this topic," he said.

Most sightings were, in fact, debunked - including a sighting in 1965 at the World's Fair later that was called "a photographic anomaly" - but 701 cases remain not fully explained in the papers.

Those cases include numerous sightings over Washington, D.C., in 1952.

"They really couldn't, at the end of the day, explain some of these more important cases," Greenewald said.

In 1969, the government announced it was no longer interested in pursuing the cases, saying that they'd found "no evidence indicating that sightings categorized as 'unidentified' are extraterrestrial vehicles."

But Greenewald said he'd never bought into the US decision.

"When I look at the documentation, I'm a believer, based on that," he said. "I believe the documentation proves beyond a shadow of a doubt that there is a coverup going on."

ABC News' Jared Wiener contributed to this story.