Since UFOs are a worldwide phenomena, most Ufologists believe that some of the world's leading governments are aware of the existence of these extraterrestrial visitors and their crafts...and have taken the appropriate steps to cover-up the data collected by various agencies.

The late Donald E. Keyhoe, a retired marine corps officer and the author of five books including Flying Saucers: Top Secret and Flying Saucers Are Real, insisted that the Air Force knew more than it was telling:

"We are being observed by some type of device which is ahead of us...far ahead of us...and probably controlled by a higher type of superior civilization. It has reached the point where many people in the Air Force have the same conclusion. In fact, the Air Force, at one time, had a top secret estimate that these things were interplanetary spaceships. Instead of being a subject for ridicule and a big joke, actually it's a serious matter which could affect the lives of all of us."

"According to the United States Air Force, and following a policy which was set probably very high in the Pentagon, there are about 250 or 300 extremely incompetent airline and military pilots in this country. Airlines let them continue to fly even though they have reported UFOs."

During another press conference, he said:

"This is not an attack on the Air Force spokesman or the project spokesman. They are simply following orders to explain away all UFO sightings as quickly as possible when they become public...and deny that UFOs really exist."

"With all due respect to the Air Force, I believe that some of them (UFOs) will prove to be of interplanetary origin."

The Department of National Defence, NORAD (North American Air Defense Command) and NASA (National Aeronautics and Space Administration) - to name a few - probably know a great deal more about UFOs than they are willing to admit publicly.

Having the best technology and equipment at their disposal for tracking any object leaving or entering Earth's orbit, it certainly makes sense that they would have recorded several instances in which strange aerial objects of unknown origin have been picked up on their detection instruments, including radar and infrared cameras.

Not to mention all the space probes that made their way to the Moon and Mars, taking hundreds of photographs of their surface and transmitting them back to Earth for processing.

What the general public may not be aware of is the fact that there is a special team at NASA whose job it is to screen every incoming photograph and look for anything unusual or suspicious - including UFOs - and airbrush them out before releasing the prints to the public.

Furthermore, the United States also had an unwritten law called The Extra-terrestrial Exposure Law which was passed in July 1969, but has since been removed from the books because "it served its purpose and is no longer in keeping with current policy." This law made it illegal for the public to come in contact with extra-terrestrials or their vehicles.