I think you have to be a bit more discriminating. A classic saucer or cigar craft can seem undeniably a nuts and bolts unit. On many of the photographs, say for instance the Trent images, you can literally identify construction details of the exterior of the craft, and so their origin resonates very strongly with this realm, this planet, even this time. They were built by individuals or groups with making abilities concisely analgous to our own, that is, I would venture to say that whoever built them has both binocular vision as well as opposable thumbs, walks upright, and is bilaterally symmetrical in physique. Joined overlapping plates of metal, any metal, and windowed interiors speak of creatures greatly if not entirely like ourselves. For this reason, my feeling is that such craft are built on Earth, that they are of contemporary build, and are built by persons or creatures indigenous to this planet. It is, though, entirely possible that a parallel society of persons or creatures embodying these traits co-exists with us here without our knowledge of them, and has for many eons. The ability of the biological sciences to firmly identify only a small percentage of the indigenous species resident here implys a vast repertoire of possibilities, the most likely being the almost completely unexplored realms of the ocean depths. The fact that many, many sighting of these types of craft involve water and oceanic backgrounds further adds to my hypothesis that there exist a species, a bipedal primate, quite advanced, which has taken back to the sea, and has renounced the pragmatic world of belching industrialism and soot filled skies for the intuitive and telepathic regions along the deepest energised lay-lined routes of the ocean bottoms vaguely known to the ancients, and from them drawing their power and stealth. They love to harrass our plodding and ineffectual airships, and to make calculated forays into the interiors of the drylands to satisfy their curious nature. But their opinions of us must resemble the opinions of whales, distant and reproving, seen through the lens of a decision made untold ages ago, to return forever to the sea.April 10, 2010 - West Midlands
Then there are the orbs, the balls of light which playfully merge and diverge restlessly in the skys, and are seen chasing airships and cavorting in unfathomable manners. Some of these are Jungian egregores, products of the universal consciousness manifested by the stresses and dreams of human thought process in areas of the brain undiscovered by the blunt scalpels and scans available to the primative trepanners of contemprary surgeries. The mind has abilities so vast and powerful that the entire scope of the last ten thousand years of human history has been one extended battle by those with much to lose to stop that power from evidencing its wonders. And yet, even so stifled by the reductions of "education" and the antipathies of "reason" and the prisons of "work", the mind makes itself known collectively, and acts to physically become real in this consciousness, just as in the unconsciousness of dreams.February 26, 2010 - Albuquerque, New Mexico
And it is true beyond debate that many of the unknown strange craft above our heads are the work of our own government, though. The triangles of huge size which are occasionally displayed for their effects of power and confusion are an obvious example of the outcome of a trillion dollars per year in black budget funds, compounded annually. Antarctic nazis are just a small branded division of this logoless transnational supercorporation.
So my answer would be "some of the above".
The most dangerous traps are the ones you set for yourself. - Phillip Marlowe