The thing I think a lot of people miss is that, if I'm not mistaken, due to his position he has to report on what he was told. It doesn't matter if it sounds insane or he doesn't have proof; his job is to tell Congress what he was told during his investigations. If he was told that it's aliens, then that's what he has to tell Congress.

I want to believe it's aliens. I think that'd be pretty cool. However, my speculation is that he was given false information by the military to try to make him sound nuts and get Congress off their backs. Either that or he wasn't given the full picture. Just because something is non-human doesn't mean it's alien in origin. It could be unmanned drones that had mice, monkeys or dogs in them to test g-forces (not sure why you couldn't use a dummy in this day and age, but that's beside the point). It could be the result of some kind of experiment to use biological matter instead of silicon and wiring. It could be aliens. There still isn't enough information for a definitive conclusion except that the US has had unidentified objects flying through controlled aerospace unimpeded.