The emerging surmise by many UFO researchers is that most UFOs are from alternate dimensions, from an advanced hidden civilization long resident on the planet, or from a future, advanced version of mankind. While the small size of the objects observed by the USN argues against their being from a distant alien civilization, it does not of necessity indicate a mundane origin in contemporary military technology.
And if some civilization is out there, and no doubt there is, why would they want to bother with us? Mankind has a disturbing predilection with it's own destruction. Were I some advanced civilization I'd avoid this place. And if some advanced civilization did happen to notice us they might not come with benign motives. They might come here and kill us all and harvest what they want from the planet.