There's no doubt that UFOs represent an incredibly complex phenomenon and the simple "flying saucers from outer space" scenario just doesn't fit. Strange things in the skies -- and strange humanoid beings -- have been reported for centuries. Maybe the fairy/jinn theory could apply. There's also no doubt that there are highly classified projects in the US that operate under the strongest form of compartmentalised security, some of these dealing with advanced propulsion systems. They managed to keep stealth totally secret for decades. And there is also no doubt that, ever since Roswell, the alien visitors notion has been actively promoted by agencies such as AFOSI. I am certain that the HIlls' alleged abduction case is an example of this. If nothing else it is a good cover story for the black projects activities. But the core phenomenon is still there -- strange aerial vehicles exhibiting incredible performance characteristics, and humanoid beings behaving in equally strange ways. I doubt that anyone in official circles really understands what is going on, the ludicrous stories about US presidents meeting aliens and the like are just designed to keep the UFO believers (believers rather than serious researchers) active and keep the noise level at max.